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1 May 2007

Volume 101, Issue 9, Articles (09xxxx)

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back to top Electronic Structure, Itinerant Magnetism

Dynamical spin response of itinerant electrons close to a quantum critical point

P. Schlottmann

J. Appl. Phys. 101, 09G501 (2007); http://dx.doi.org/10.1063/1.2667522 (3 pages)

Online Publication Date: 19 March 2007

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The dynamical spin susceptibility χ″(ω,Q), which is of relevance to inelastic neutron scattering, is calculated for an itinerant antiferromagnet (AF) close to a quantum critical point (QCP). The model consists of nested Fermi surfaces of an electron pocket and a hole pocket separated by a wave vector Q, which give rise to itinerant AF for a repulsive interaction between the carriers. The order can gradually be suppressed by mismatching the nesting and a QCP is obtained as TN→0. For the tuned QCP a quasielastic peak in χ″(ω,Q) with a linewidth proportional to T is obtained.
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75.10.Lp Band and itinerant models
75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.30.Cr Saturation moments and magnetic susceptibilities
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor

Surface electronic structure and magnetism of NiAs structured MnAs(0001) and MnSb(0001)

J. I. Lee and S. C. Hong

J. Appl. Phys. 101, 09G502 (2007); http://dx.doi.org/10.1063/1.2670093 (3 pages) | Cited 1 time

Online Publication Date: 20 March 2007

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We investigated the surface electronic structure and magnetism of the NiAs structured MnAs(0001) and MnSb(0001) using first-principles full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation. We considered the Mn- and anion(As or Sb)-terminated surfaces for both the MnAs(0001) and MnSb(0001) systems. The calculated magnetic moments of the surface Mn atoms for Mn-terminated MnAs(0001) and MnSb(0001) systems are much enhanced to have 3.79μB and 4.04μB, respectively, compared to the corresponding center layer values, 3.10μB and 3.32μB. The anion atoms in the Mn- and anion-terminated systems have negative magnetic moments with the values between −0.09μB and −0.18μB. The effects of surface termination and the band hybridization on the magnetism and the electronic structure are discussed with the calculated density of states.
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73.20.At Surface states, band structure, electron density of states
75.70.Rf Surface magnetism
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Dd Nonmetallic ferromagnetic materials

Noncollinear magnetism in Permalloy

Markus Eisenbach, G. Malcolm Stocks, and Don M. Nicholson

J. Appl. Phys. 101, 09G503 (2007); http://dx.doi.org/10.1063/1.2670151 (3 pages)

Online Publication Date: 21 March 2007

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Permalloy is an important material in a wide variety of magnetic systems, most notably in giant-magnetoresistive read heads. However, despite this great interest, its properties are not fully understood. For an in depth analysis of important physical properties as, e.g., electric transport or magnetic anisotropy, a detailed understanding of the distribution of magnetic moments on an atomic level is necessary. Using our first principles locally self-consistent multiple scattering method, we calculate the magnetic ground state structure for a large supercell model of Permalloy. Our code allows us to solve both the usual nonrelativistic Schrödinger equation as well as the fully relativistic Dirac equation and to find the magnitude and direction of the magnetic moments at each atomic site. While the nonrelativistic calculation yields a collinear ground state in accordance with previous calculations, we find the ground state for the fully relativistic calculation to be slightly noncollinear. We also investigate the influence of variations in the iron concentration on the distribution of magnetic moments.
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75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Mg Numerical simulation studies

Stark effect on quantum well states in Au/Fe(100)

S. Ogawa, S. Heike, H. Takahashi, and T. Hashizume

J. Appl. Phys. 101, 09G504 (2007); http://dx.doi.org/10.1063/1.2709410 (3 pages) | Cited 1 time

Online Publication Date: 23 March 2007

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The quantum well (QW) states in Au/Fe(100) and their energy dependence on tip-sample distance are observed using scanning tunneling spectroscopy. When the tip-sample distance is decreased by 0.2 nm, the QW states shift by as large as 40 meV, which is approximately 20 times larger than the Stark shift observed in the surface state in noble metals. The observed shifts may be caused by the phase shift of the QW wave functions in the Au film as well as at the vacuum∕Au interface.
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73.21.Fg Quantum wells
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
73.20.At Surface states, band structure, electron density of states
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films

Ferromagnetic one dimensional Ti atomic chain

Jisang Hong

J. Appl. Phys. 101, 09G505 (2007); http://dx.doi.org/10.1063/1.2667857 (3 pages) | Cited 1 time

Online Publication Date: 27 March 2007

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Using the full potential linearized augmented plane wave method, we have explored the magnetic properties of one dimensional (1D) Ti atomic chain. Interestingly, we have observed that the 1D Ti atomic chain has ferromagnetic ground state even on NiAl(110) surface. In addition, it has been found that the magnetic dipole interaction is a key factor in the study of magnetic anisotropy, not the magnetocrystalline anisotropy arising from spin-orbit interaction.
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75.75.-c Magnetic properties of nanostructures
75.50.Cc Other ferromagnetic metals and alloys
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Gw Magnetic anisotropy
73.21.Hb Quantum wires
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Calculations of spin-disorder resistivity from first principles

A. L. Wysocki, K. D. Belashchenko, J. P. Velev, and M. van Schilfgaarde

J. Appl. Phys. 101, 09G506 (2007); http://dx.doi.org/10.1063/1.2670472 (3 pages) | Cited 2 times

Online Publication Date: 28 March 2007

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Spin-disorder resistivity of Fe and Ni is studied using the noncollinear density functional theory. The Landauer conductance is averaged over random disorder configurations and fitted to Ohm’s law. The distribution function is approximated by the mean-field theory. The dependence of spin-disorder resistivity on magnetization in Fe is found to be in excellent agreement with the results for the isotropic s‐d model. In the fully disordered state, spin-disorder resistivity for Fe is close to experiment, while for fcc Ni it exceeds the experimental value by a factor of 2.3. This result indicates strong magnetic short-range order in Ni at the Curie temperature.
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75.50.Cc Other ferromagnetic metals and alloys
75.50.Bb Fe and its alloys
75.50.Kj Amorphous and quasicrystalline magnetic materials
75.40.Mg Numerical simulation studies
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.10.Nr Spin-glass and other random models

Magnetocapacitance in a ferromagnetic metal tunnel junction system

Kyoo Kim and B. I. Min

J. Appl. Phys. 101, 09G507 (2007); http://dx.doi.org/10.1063/1.2710338 (3 pages) | Cited 1 time

Online Publication Date: 30 March 2007

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We have studied the magnetocapacitance (MC) of a ferromagnetic (FM) metal-oxide-FM metal tunnel junction. The capacitance changes linearly as the magnetic field increases, and its amount depends on the shape of the density of state at the Fermi level of a FM metal. We have also investigated the effect of the bandwidth change induced by the electron-electron interaction on the MC. We have found that the effect of the bandwidth change on the MC can be substantial near the magnetic phase boundary.
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75.80.+q Magnetomechanical effects, magnetostriction
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Magnetic transitions in manganese benzoquinone coordination polymers

R. R. Rakhimov, R. Bah, A. Andreyev, T. Chisholm, N. Noginova, J. S. Hwang, A. I. Prokof’ev, S. P. Solodovnikov, I. A. Alexandrov, and A. I. Aleksandrov

J. Appl. Phys. 101, 09G508 (2007); http://dx.doi.org/10.1063/1.2710450 (3 pages)

Online Publication Date: 2 April 2007

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Coordination polymers exhibiting magnetic properties can be considered as promising materials for magnetic applications. We obtained such materials by means pf mechanochemical incorporation of binuclear metal complexes Mn–O–Mn into polystyrene. Incorporation of binuclear manganese complexes was achieved by using substituted benzoquinones (organic acceptors) as intermediate ligands that react with manganese acetylacetonate and provide new coordination and stabilization of manganese in different valence states. Magnetic transitions in this system are due to reversible disproportionation process Mn3+–O–Mn3+⇔Mn2+–O–Mn4+ in the binuclear complex. The structure of the binuclear complex was obtained using ab initio calculations.
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75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
61.41.+e Polymers, elastomers, and plastics

Antiferromagnetic fluctuations in the quantum phase transition of the one-dimensional electron system

Norikazu Tomita

J. Appl. Phys. 101, 09G509 (2007); http://dx.doi.org/10.1063/1.2710809 (3 pages)

Online Publication Date: 3 April 2007

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Quantum antiferromagnetic (AF) fluctuations that promote the charge-density-wave (CDW)-AF state phase transition in the one-dimensional (1D) extended Hubbard model are clarified for the strong correlation regime. It is clearly shown that the CDW wave function contains quantum fluctuations due to the AF domains near the phase boundary. Though the size of these AF domains stays finite, its density to the system size becomes asymptotically zero in the infinite-size limit. This indicates the quantum decoherence, or the first order phase transition between the CDW and AF state. On the other hand, the survived AF domains would naturally evolve into the quantum nucleation that triggers the CDW-AF state phase transition.
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75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.10.Lp Band and itinerant models
75.60.Ch Domain walls and domain structure
71.45.Lr Charge-density-wave systems

Role of orbital degeneracy in itinerant ferromagnetism

Piyush Dua and Ishwar Singh

J. Appl. Phys. 101, 09G510 (2007); http://dx.doi.org/10.1063/1.2709422 (3 pages)

Online Publication Date: 4 April 2007

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In this work we have considered a doubly degenerate extended Hubbard model to study the magnetic (and optical) properties of itinerant ferromagnets such as Fe, Co, Ni, and their compounds. Using Green’s function equation of motion technique, we have studied ground state phase diagram as a function of band filling n. Our results for magnetization M as a function of n reproduce the observed behavior of Fe1−xCoxS2, Co1−xNixS2. We have studied magnetic susceptibility, magnetoresistance, spectral weight, and effective mass as a function of temperature. We have found that in the presence of magnetic field, the effective mass for up-spin electrons decreases and their spectral weight increases at all temperatures. The reduction of the effective mass of up-spin electrons, on applying magnetic field, has been observed in EuB6.
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75.50.Bb Fe and its alloys
75.50.Cc Other ferromagnetic metals and alloys
75.50.Dd Nonmetallic ferromagnetic materials
75.10.Lp Band and itinerant models
71.10.Hf Non-Fermi-liquid ground states, electron phase diagrams and phase transitions in model systems
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor

Effect of pressure on the itinerant ferromagnet CoS2: A first-principles study

X. B. Liu and Z. Altounian

J. Appl. Phys. 101, 09G511 (2007); http://dx.doi.org/10.1063/1.2710955 (3 pages) | Cited 1 time

Online Publication Date: 5 April 2007

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Electronic structure and magnetic properties of CoS2 with a cubic-pyrite-type structure have been studied by a first-principles density functional theory (DFT) calculation using a linear muffin-tin orbital method within the framework of the generalized gradient approximation for the treatment of exchange-correlation effects. The total energy and magnetic moments are calculated as a function of lattice constant. The calculated lattice constant and magnetic moments are in good agreement with the experimental results. The pressure-volume relationship is obtained by fitting the calculated total energy to the universal equation of state. The derived bulk modulus is 137 GPa and the equilibrium volume is 42.16 Å3/f.u. The calculated Co magnetic moment decreases at a rate of −0.0055 μB/GPa as the external pressure less than 3.6 GPa, in agreement with the experimental value of −0.005 μB/GPa. The DFT calculations predict the occurrence of a first order pressure induced magnetic transition in CoS2 at a high pressure (12 GPa), which is qualitatively consistent with the experimental data which show that the ferromagnetic state in CoS2 is unstable at external pressures higher than 6 GPa.
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71.20.Ps Other inorganic compounds
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Et Exchange and superexchange interactions
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
81.40.Jj Elasticity and anelasticity, stress-strain relations
62.20.D- Elasticity

Annealing temperature dependence of the electronic structure of La0.7Ca0.3MnO3−δ perovskite

J. S. Park, Y. P. Lee, and Youn-Seoung Lee

J. Appl. Phys. 101, 09G512 (2007); http://dx.doi.org/10.1063/1.2712302 (3 pages) | Cited 1 time

Online Publication Date: 9 April 2007

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The local atomic and electronic structures of La0.7Ca0.3MnO3 (LCMO) prepared by solid-state reaction was investigated at different annealing temperatures (TA). We employed x-ray absorption spectroscopy and x-ray photoemission spectroscopy to understand the local atomic and electronic structures of the LCMO system. Both the atomic and electronic structures due to the oxygen deficiency in LCMO turn out to change with increasing TA. Especially, the eg ↑ states, leading to the ferromagnetic interaction, are reduced by the diminution of Mn 3d–O 2p hybridization with increasing TA.
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71.20.Ps Other inorganic compounds
81.40.Gh Other heat and thermomechanical treatments
75.50.Dd Nonmetallic ferromagnetic materials
78.70.Dm X-ray absorption spectra
79.60.Bm Clean metal, semiconductor, and insulator surfaces
75.30.Et Exchange and superexchange interactions

Electronic structures and magnetic properties of layered compound RCrSb3 (R = La,Yb)

H. C. Choi, J. H. Shim, S. K. Kwon, and B. I. Min

J. Appl. Phys. 101, 09G513 (2007); http://dx.doi.org/10.1063/1.2710335 (3 pages) | Cited 3 times

Online Publication Date: 17 April 2007

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RCrSb3 (R: rare-earth ions) exhibits unconventional magnetic behaviors due to their layered structures and the complex interactions of Cr 3d and R 4f electrons. We have explored the electronic structures of LaCrSb3, YbCrSb3, and also LaVSb3 for a comparison by using the linearized muffin-tin orbital band method. For LaCrSb3 and LaVSb3, the rigid band model is well applicable to understanding their electronic and magnetic states. However, for LaCrSb3 and YbCrSb3, the extension of the rigid band model fails, because Yb ions in YbCrSb3 are in a divalent state of Yb2+ with fully occupied 4f bands, which differ from the trivalent La3+ in LaCrSb3.
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71.20.Ps Other inorganic compounds
75.30.Cr Saturation moments and magnetic susceptibilities
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Metamagnetic transitions in RFe2(H,D)4.2 compounds (R = Y,Tb)

T. Leblond, V. Paul-Boncour, M. Guillot, and O. Isnard

J. Appl. Phys. 101, 09G514 (2007); http://dx.doi.org/10.1063/1.2710456 (3 pages) | Cited 3 times

Online Publication Date: 17 April 2007

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The Tb for Y substitution in YFe2D4.2 leads to an increase of cell volume, a canted ferrimagnetic structure at low temperature, and a shift of the magnetovolumic transition temperature to higher value. The study of the structural and magnetic properties of TbFe2H4.2 and TbFe2D4.2 indicates a significant (H,D) isotope effect implying a larger cell volume and a higher transition temperature for the hydride compared to the deuteride.
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75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.80.+q Magnetomechanical effects, magnetostriction
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.50.Gg Ferrimagnetics

Hole-mediated interactions of Mn acceptors on GaAs (110) (invited)

D. Kitchen, A. Richardella, P. Roushan, J.-M. Tang, M. E. Flatté, and A. Yazdani

J. Appl. Phys. 101, 09G515 (2007); http://dx.doi.org/10.1063/1.2694511 (6 pages) | Cited 5 times

Online Publication Date: 23 April 2007

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A scanning-tunneling-microscopy-substitution technique is used to incorporate single Mn atoms into Ga sites in GaAs (110) surfaces. The electronic states near a single Mn in the acceptor configuration produce a strong in-gap resonance associated with the acceptor level. The isolated Mn acceptor is probed in both p-type and n-type environments to access the neutral and ionized acceptor configurations. The Mn acceptor at the surface substitution site shares bulk characteristics that compare well with tight-binding calculations. The anisotropic structure of the Mn hole state plays an important role in hole-mediated interactions between the Mn acceptors. Isolated Mn pairs show a strong interaction dependence on crystal orientation and spacing. Certain pair orientations produce a strong splitting of the acceptor level into two levels with bondinglike and antibondinglike symmetries. A tight-binding model relates the acceptor level splitting and the spin-spin interaction energy J.
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73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.55.Eq III-V semiconductors
71.70.-d Level splitting and interactions
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
76.60.-k Nuclear magnetic resonance and relaxation

Powder neutron diffraction evidence for enhanced inter plane magnetic coupling in La1.2Sr1.8Mn2−xRuxO7 layered manganites

S. Sundar Manoharan, Brajendra Singh, and R. K. Sahu

J. Appl. Phys. 101, 09G516 (2007); http://dx.doi.org/10.1063/1.2696636 (3 pages) | Cited 4 times

Online Publication Date: 24 April 2007

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Rotation of Mn spin moments along the c axis enhances interplane magnetic coupling, leading to a steep increase in the Curie temperature (TC) and metal to insulator transition (TMIT) in Ru substituted two dimensional layered manganites, La1.2Sr1.8Mn2−xRuxO7. The temperature dependent neutron diffraction data show the absence of (004) reflection, indicating that the Mn spin moments are not aligned in the a-b plane, and rather the increase in intensity of (110) reflection at 12 K shows that the MnO2 layers are stacked ferromagnetically along the c axis. The presence of Ru at the Mn site in pentavalent state assures the required hole carrier density for a sustained double-exchange interaction. The cumulative effect of rotation of Mn spin moments and the variable valence states of Ru lead to a pronounced increase in TC up to ∼ 50 K, which is not observed hitherto in any of the B-site substituted manganites.
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75.50.Dd Nonmetallic ferromagnetic materials
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.30.Et Exchange and superexchange interactions
71.30.+h Metal-insulator transitions and other electronic transitions

Strongly enhanced thermal expansion of low-dimensional itinerant weak antiferromagnets near the quantum critical points

Rikio Konno, Yoshinori Takahashi, and Hiroki Nakano

J. Appl. Phys. 101, 09G517 (2007); http://dx.doi.org/10.1063/1.2711278 (3 pages) | Cited 2 times

Online Publication Date: 1 May 2007

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The thermal expansion of low-dimensional itinerant antiferromagnetic metals is discussed along with the recent study on the magneto-volume effect by Takahashi and Nakano [J. Phys.: Condens. Matter 16, 4505 (2004) ]. In this study, we find that the thermal volume expansion derived by Takahashi and Nakano shows a stronger enhancement of the T-linear slope of the thermal expansion coefficient proportional to y−1/2 and ln(1/y), respectively, for one-dimensional and two-dimensional (2D) systems than that of three dimensions as we approach the magnetic instability point (y→0), where y is the inverse of the reduced staggered magnetic susceptibility. On the other hand, the same coefficient for the conventional term by Moriya and Usami [Solid State Commun. 34, 95 (1980) ] is suppressed proportional to 1/ln(1/y) for 2D systems. The present result suggests that the temperature dependence of low-dimensional weak antiferromagnets is generally dominated by the strongly enhanced T2-linear thermal expansion from the magnetic origin.
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75.80.+q Magnetomechanical effects, magnetostriction
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
75.30.Cr Saturation moments and magnetic susceptibilities
75.10.Lp Band and itinerant models
65.40.De Thermal expansion; thermomechanical effects

Low temperature neutron diffraction studies showing evidence for charge-exchange-type magnetic ordering in Mn doped SrRuO3

Brajendra Singh, S. Sundar Manoharan, R. K. Sahu, P. S. R. Krishnan, A. B. Shinde, and Karishma Jain

J. Appl. Phys. 101, 09G518 (2007); http://dx.doi.org/10.1063/1.2711417 (3 pages)

Online Publication Date: 2 May 2007

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SrRuO3 is a 4d transition metal oxide having a metallic and itinerant ferromagnetic character with TC ∼ 165 K. Mn doping in SrRuO3 induces antiferromagnetic interaction, with the equiatomic composition SrRu0.5Mn0.5O3 showing TC ∼ 125 K. Temperature dependent zero field cooled and field cooled magnetization data, resistivity data, and neutron diffraction studies on SrRu0.5Mn0.5O3 show the signature of the presence of two ferromagnetic zigzag chains coupled antiferromagnetically, called charge exchange (CE)-type antiferromagnetic ordering; this is contrary to the role of Ru+4, which is reported to remove charge ordering in manganites. The presence of significant amount of Mn+3 ions plays an important role in stabilizing the CE-type antiferromagnetic ordering.
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75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Dd Nonmetallic ferromagnetic materials

Photoemission study of the Fe(001)/MgO interface for varying oxidation conditions of magnesium oxide

Martina Müller, Frank Matthes, and Claus M. Schneider

J. Appl. Phys. 101, 09G519 (2007); http://dx.doi.org/10.1063/1.2711418 (3 pages) | Cited 2 times

Online Publication Date: 2 May 2007

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The nature of interface bonding essentially determines the spin polarization of tunneling currents through ferromagnet/insulator interfaces. We focus on the influence of ultrathin off-stoichiometric MgO coverages on the spin-polarized electronic structure of the (001) surface of bcc-Fe. By applying a combination of low-energy spin-resolved and core-level photoelectron spectroscopy, we show that the MgO stoichiometry has a direct impact on the interfacial spin polarization. The results underline the importance of controlling the chemical composition and bonding at ferromagnet/oxide interfaces to further optimize spin-dependent tunneling devices.
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72.25.Mk Spin transport through interfaces
82.80.-d Chemical analysis and related physical methods of analysis
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
79.60.Jv Interfaces; heterostructures; nanostructures

Induced effects by the substitution of Mg in MgCNi3

Guohua Zhong, Jianglong Wang, Zhi Zeng, Xiaohong Zheng, and Haiqing Lin

J. Appl. Phys. 101, 09G520 (2007); http://dx.doi.org/10.1063/1.2711703 (3 pages) | Cited 3 times

Online Publication Date: 2 May 2007

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The electronic structures and magnetic properties induced by the substitution of Mg in MgCNi3 were investigated by performing the first-principles density functional calculations. It is confirmed that AlCNi3, GaCNi3, and InCNi3 are paramagnetic nonsuperconductors resulting from total energy, density of states at Fermi level, and electron-phonon coupling constant. A large peak of density of states lies on the Fermi level, resulting in ferromagnetism rather than superconductivity in NaCNi3. The substitution of dual elements for Mg, such as Al0.5Na0.5CNi3 and Al0.5Li0.5CNi3, was inspected too. Evaluating the electron-phonon coupling interaction, the possible superconductivity exists in near ferromagnetic Al0.5Na0.5CNi3.
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75.20.En Metals and alloys
75.50.Cc Other ferromagnetic metals and alloys
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.40.Cx Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
71.20.Eh Rare earth metals and alloys
71.20.Be Transition metals and alloys

Noncollinear magnetism, magnetocrystalline anisotropy, and spin-spiral structures in Fe/W(110)

Kohji Nakamura, Naoki Mizuno, Toru Akiyama, Tomonori Ito, and A. J. Freeman

J. Appl. Phys. 101, 09G521 (2007); http://dx.doi.org/10.1063/1.2713225 (3 pages) | Cited 5 times

Online Publication Date: 4 May 2007

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Spin-spiral structures in the Fe monolayer on a W(110) substrate are determined by means of the first principles film full-potential linearized augmented plane-wave method including full-noncollinear magnetism. The results obtained predict that spin-spiral structures with a wave vector of 0.05a−1–0.1a−1, where a is the lattice constant of bulk W, are energetically favorable over the ferromagnetic (FM) state. When compared with the calculated magnetocrystalline anisotropy (MCA) energy, however, the formation of the spin-spiral structures may be suppressed due to the large MCA that arises from the strong spin-orbit coupling at the Fe/W(110) interface, and so the system appears to be the FM state—as observed in experiments.
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75.70.Ak Magnetic properties of monolayers and thin films
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Bb Fe and its alloys
75.30.Gw Magnetic anisotropy
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect

Correlation effect and magnetic moments in Cr2Te3

S. J. Youn, S. K. Kwon, and B. I. Min

J. Appl. Phys. 101, 09G522 (2007); http://dx.doi.org/10.1063/1.2713699 (3 pages) | Cited 1 time

Online Publication Date: 4 May 2007

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The electronic and magnetic structures of Cr2Te3 have been studied theoretically using the linearized muffin-tin orbitals band method. Experimental photoemission spectra and magnetic moments can be described better when the on-site Coulomb correlation U of Cr 3d electrons is considered using the local spin-density approximation+U method. The proper size of U is found to be U ∼ 1.7 eV. The complex magnetic behaviors of Cr2Te3 come from the degeneracy of parallel and antiparallel alignments of CrI spin to CrII and CrIII spins.
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75.30.Cr Saturation moments and magnetic susceptibilities
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
71.20.Ps Other inorganic compounds
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
71.15.Mb Density functional theory, local density approximation, gradient and other corrections

Valence states of transition-metal ions in cubic perovskites SrMn1−xFexO3

H. J. Lee, G. Kim, J.-S. Kang, B. Dabrowski, S. W. Han, S. S. Lee, C. Hwang, M. C. Jung, H. J. Shin, H. G. Lee, J.-Y. Kim, and B. I. Min

J. Appl. Phys. 101, 09G523 (2007); http://dx.doi.org/10.1063/1.2713206 (3 pages) | Cited 1 time

Online Publication Date: 4 May 2007

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The electronic structures of SrMn1−xFexO3 (0 ⩽ x ⩽ 1) have been investigated by using photoemission spectroscopy (PES) and soft x-ray absorption spectroscopy (XAS). Mn ions in SrMnO3 are found to be in the nearly tetravalent (Mn4+) states, but with a small mixture of the Mn2+ configuration. With increasing x in SrMn1−xFexO3, Mn ions remain in the 4+ states. Fe ions in SrMn1−xFexO3 are also in the nearly tetravalent (Fe4+) states for the whole range of x. Valence-band PES reveals that the occupied Mn t2g3 states are located about 2.5 eV below EF, while the occupied Fe t2g3eg1 states are broader than the Mn 3d occupied states, and are located between 3 and 6 eV below EF. The large overlap between Fe 3d and the O 2p states is found in SrFeO3, reflecting the strong hybridization between the Fe 3d states and the O 2p states, in agreement with the metallic nature of SrFeO3.
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71.20.Ps Other inorganic compounds
78.70.Dm X-ray absorption spectra
79.60.-i Photoemission and photoelectron spectra

Magnetic impurities in magic-number clusters

Ralph Skomski and D. J. Sellmyer

J. Appl. Phys. 101, 09G524 (2007); http://dx.doi.org/10.1063/1.2713228 (3 pages)

Online Publication Date: 7 May 2007

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It is investigated how magnetic impurities modify the behavior of metallic clusters. Two complementary models are used, an s-d exchange model with a stable magnetic moment and a Hubbard-type Kondo model. The s-d and s-f interactions are modeled by a pointlike potential, as in the Ruderman-Kittel-Kasuya-Yosida approximation, but the perturbed levels are obtained by diagonalizing the interaction matrix rather than using perturbation theory. The spin polarization of the conduction electrons due to the magnetic impurities leads to a reduction of the highest occupied molecular orbital–lowest unoccupied molecular orbital splitting. A particularly interesting case is Pt, which is used in catalysis and whose well-delocalized 5d electrons are easily spin polarized by conduction electrons. Strikingly, the simplest realization of the Kondo effect is reproduced by an unrestricted Hartree-Fock approximation.
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75.30.Hx Magnetic impurity interactions
75.30.Et Exchange and superexchange interactions
71.70.Gm Exchange interactions
75.30.Mb Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
75.20.Hr Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions
75.30.Cr Saturation moments and magnetic susceptibilities
75.10.Lp Band and itinerant models

Temperature dependent x-ray magnetic circular dichroism in Er2Fe17

Y. Lee, B. N. Harmon, A. I. Goldman, and J. C. Lang

J. Appl. Phys. 101, 09G525 (2007); http://dx.doi.org/10.1063/1.2713428 (3 pages) | Cited 2 times

Online Publication Date: 7 May 2007

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The x-ray magnetic circular dichroism spectra of the erbium L2 and L3 edges in Er2Fe17 have been investigated experimentally as a function of temperature and theoretically using first principles electronic structure calculations. The spectral changes with temperature are rather dramatic and are related to the interplay between the Fe-3d and the Er-4f orbitals causing spin polarization of the 5d states.
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75.50.Bb Fe and its alloys
78.20.Ls Magneto-optical effects
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