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15 May 2003

Volume 93, Issue 10, pp. 5855-8792

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Overlayer and superlattice studies of metal/ceramic interfaces: Fe/TiC

Tatsuya Shishidou, Joo-Hyoung Lee, Yu-Jun Zhao, Arthur J. Freeman, and Gregory B. Olson

J. Appl. Phys. 93, 6876 (2003); http://dx.doi.org/10.1063/1.1556151 (3 pages) | Cited 7 times

Online Publication Date: 9 May 2003

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Adhesion and magnetism at the Fe(001)/TiC(001) interface, studied by first-principles calculations using the full-potential linearized augmented plane wave method, show that the interfacial Fe and C atoms can form significantly strong covalent bonding, which makes the interface structure with Fe sitting on top of C as the most stable structure for both overlayers and superlattices. Due to this strong bonding, the first layer of Fe at the interface shows a considerably reduced magnetic moment (−20%), while the second layer almost recovers its bulk value. The interface C atom has a negative spin polarization, while the interface Ti atom has a positive magnetic moment. © 2003 American Institute of Physics.
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68.35.Ct Interface structure and roughness
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
68.35.Np Adhesion
75.30.Cr Saturation moments and magnetic susceptibilities

First principles investigation of domain walls and exchange stiffness in ferromagnetic Fe and antiferromagnetic NiMn

Kohji Nakamura, Tomonori Ito, A. J. Freeman, Lieping Zhong, and Juan Fernandez-de-Castro

J. Appl. Phys. 93, 6879 (2003); http://dx.doi.org/10.1063/1.1556152 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

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We investigate the domain walls in ferromagnetic Fe and antiferromagnetic NiMn with the first principles full-potential linearized augmented plane-wave method including intra-atomic noncollinear magnetism. In both cases, the self-consistent results demonstrate that the magnetization changes continuously from one orientation to another as seen in a Bloch wall. The formation energy of the domain wall (ΔEDW) significantly decreases when the wall thickness increases, which leads to an exchange stiffness of 1.13×10−11 J/m for Fe and 1.43×10−11 J/m for NiMn. The predictions agree with those determined separately for Fe from a phenomenological calculation. © 2003 American Institute of Physics.
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75.60.Ch Domain walls and domain structure
75.30.Et Exchange and superexchange interactions
75.50.Bb Fe and its alloys
75.50.Ee Antiferromagnetics
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)

Magneto-structural phase transition in Gd5(Si2Ge2) and MnFe(P1/3As2/3) systems

G. D. Samolyuk and V. P. Antropov

J. Appl. Phys. 93, 6882 (2003); http://dx.doi.org/10.1063/1.1556153 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

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We study the electronic structure and magnetic properties of Gd5(Si2Ge2) and MnFe(P1/3As2/3) system of alloys using the density functional approach. The stability of their magnetic structures was investigated. The total energy as a function of structural deformation was calculated. The exchange coupling calculations show that the effective Heisenberg model parameters are decreased with structural deformation. The free energy as a function of temperature and deformation was calculated. The decrease of effective exchange coupling leads to first order magneto-structural phase transition, ∣∂H/∂T∣ and giant magneto-caloric effect. © 2003 American Institute of Physics.
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75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
64.70.K- Solid-solid transitions
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
62.20.F- Deformation and plasticity
75.30.Sg Magnetocaloric effect, magnetic cooling
75.40.-s Critical-point effects, specific heats, short-range order
75.10.Jm Quantized spin models, including quantum spin frustration
71.20.Be Transition metals and alloys
71.20.Eh Rare earth metals and alloys
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
71.15.Nc Total energy and cohesive energy calculations
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
71.70.Gm Exchange interactions
75.30.Et Exchange and superexchange interactions
65.40.G- Other thermodynamical quantities

Electronic structure of Li3FeN2, a nearly half-ferromagnetic metal?

W. Y. Ching, Yong-Nian Xu, and Paul Rulis

J. Appl. Phys. 93, 6885 (2003); http://dx.doi.org/10.1063/1.1541636 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2003

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The electronic structure and magnetic properties of crystalline Li3FeN2 were studied by a first-principles method. It is shown that Li3FeN2 is nearly a half metal with a large degree of spin polarization at the Fermi level. The calculated Fe moment of 1.49μB is in good agreement with the measured value. It is also shown that the ferromagnetic interaction is along the one-dimensional chain of Fe atoms, modified by the large degree of polarization of the Li ions. Based on the analysis of the spin-polarized band structure and the density of states, it is argued that a genuine half metal in the ternary Fe nitride compounds may be possible. © 2003 American Institute of Physics.
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71.20.Nr Semiconductor compounds
75.50.Pp Magnetic semiconductors
72.25.Hg Electrical injection of spin polarized carriers
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)

Magnetic properties of SmCo5 and YCo5

P. Larson and I. I. Mazin

J. Appl. Phys. 93, 6888 (2003); http://dx.doi.org/10.1063/1.1556154 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

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We have studied the magnetic moments and magnetic anisotropy energy (MAE) of YCo5 and SmCo5 using full-potential linear augmented plane wave (LAPW) electronic structure calculations. Most previous calculations of the MAE for YCo5, using local density approximation (LDA) for the exchange-correlation potential, have found values significantly smaller (∼0.6 meV/f.u.) than experiment (∼3.8 meV/f.u.). The rest of the MAE is attributed to many body corrections. Our LAPW calculations using the generalized gradient approximation (GGA) instead of LDA and including nonspherical corrections give values ∼1.5 meV/f.u. The Co magnetic moment of YCo5−xCux, unlike the prediction of the virtual crystal approximation, decreases slowly with impurity concentration until dropping suddenly to zero at a critical dopant concentration. Correlation effects were found to be crucial for the MAE in SmCo5. While GGA calculations give MAE for SmCo5 of the wrong sign, including the LDA+U, correction brings it to ∼21 meV/f.u., in good agreement with the experimental value of 13–16 meV/f.u. © 2003 American Institute of Physics.
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75.50.Ww Permanent magnets
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Gw Magnetic anisotropy
71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)
75.10.Lp Band and itinerant models
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
75.50.Cc Other ferromagnetic metals and alloys
75.30.Hx Magnetic impurity interactions

Electronic structure of heavy fermion superconductor CeMIn5 (M=Co,Rh,Ir)

J. L. Wang, Z. Zeng, Q. Q. Zheng, and H. Q. Lin

J. Appl. Phys. 93, 6891 (2003); http://dx.doi.org/10.1063/1.1556155 (3 pages) | Cited 6 times

Online Publication Date: 9 May 2003

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The electronic structure of heavy fermion superconductor CeMIn5 (M=Co,Rh,Ir) is studied by density functional theory. Our results indicate that the MIn2 layer plays an important role for stabilizing the layered crystal structure and determining the antiferromagnetic or paramagnetic ground state in this series. When the strong correlation effects of 4f electrons beyond the local density approximation (LDA) are taken into account by the LDA+U approach, the calculated total magnetic moment and band structure of CeRhIn5 yield a good agreement with the experiment. The LDA+U calculation shows that the 4f electrons in this series are located on the border between localization and itineracy. © 2003 American Institute of Physics.
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74.70.Tx Heavy-fermion superconductors
74.25.Jb Electronic structure (photoemission, etc.)
71.27.+a Strongly correlated electron systems; heavy fermions
75.50.Ee Antiferromagnetics
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
75.30.Cr Saturation moments and magnetic susceptibilities

Optical studies of lattice and charge excitations in La1.2(Sr1.8−xCax)Mn2O7

H. L. Liu, J. L. Her, C. H. Shen, and R. S. Liu

J. Appl. Phys. 93, 6894 (2003); http://dx.doi.org/10.1063/1.1556156 (3 pages)

Online Publication Date: 9 May 2003

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Optical and Raman-scattering studies of layered La1.2(Sr1.8−xCax)Mn2O7 manganites are presented as a function of temperature and doping (x=0.0, 0.4, 0.6, and 0.8). The substitution of Ca2+ for Sr2+ leads to the suppression of the low-frequency optical spectral weight with decreasing Tc. Moreover, the observed anomalies of the Raman phonon parameters near Tc are most likely due to a strong spin-phonon coupling caused by the oxygen phonon modulation of the Mn–Mn spin exchange interaction. Our results provide important insight into the interplay of lattice, spin, and charge dynamics in these materials. © 2003 American Institute of Physics.
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78.30.Hv Other nonmetallic inorganics
75.47.Lx Magnetic oxides
63.20.-e Phonons in crystal lattices
75.30.Et Exchange and superexchange interactions
75.50.Dd Nonmetallic ferromagnetic materials
75.20.Ck Nonmetals
71.70.Gm Exchange interactions
71.30.+h Metal-insulator transitions and other electronic transitions

Theoretical and experimental studies of cyclotron resonance in p-type InAs and InMnAs at ultrahigh magnetic fields

G. D. Sanders, Y. Sun, C. J. Stanton, G. A. Khodaparast, J. Kono, Y. H. Matsuda, N. Miura, T. Slupinski, A. Oiwa, and H. Munekata

J. Appl. Phys. 93, 6897 (2003); http://dx.doi.org/10.1063/1.1556157 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2003

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We report theoretical and experimental ultrahigh magnetic field cyclotron resonance (CR) studies of paramagnetic p-type InAs and InMnAs. Experimental results are compared with an 8 band Pidgeon–Brown model which includes (i) the wave vector dependence of the electronic states along the magnetic field, and (ii) s–d and p–d exchange interactions with Mn ions. CR spectra are computed using Fermi’s golden rule. Results show two strong peaks associated with heavy and light hole transitions. Line shapes of the transitions provide information on the carrier densities. © 2003 American Institute of Physics.
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76.40.+b Diamagnetic and cyclotron resonances
75.50.Pp Magnetic semiconductors
75.20.Ck Nonmetals
71.70.Gm Exchange interactions
75.10.Lp Band and itinerant models

Magnetic second harmonic generation in centrosymmetric CoO, NiO, and KNiF3

M. Fiebig, Th. Lottermoser, V. V. Pavlov, and R. V. Pisarev

J. Appl. Phys. 93, 6900 (2003); http://dx.doi.org/10.1063/1.1556158 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2003

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Optical second harmonic (SH) spectroscopy in the centrosymmetric antiferromagnets CoO, NiO, and KNiF3 reveals pronounced signals below the Néel temperature which couple quadratically to the magnetic order parameter. The SH process roots in resonance enhanced magnetic-dipole and electric-dipole excitations between the 3d levels of the transition-metal ions in the crystal field. Different magnetic structures and differently oriented T and S domains are distinguished with a high degree of discrimination, thus demonstrating the feasibility of nonlinear optical techniques for a spatially resolved investigation of antiferromagnetic crystals and thin films. © 2003 American Institute of Physics.
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75.50.Ee Antiferromagnetics
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.60.Ch Domain walls and domain structure
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
75.10.Dg Crystal-field theory and spin Hamiltonians
71.70.Ch Crystal and ligand fields
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.70.Ak Magnetic properties of monolayers and thin films
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