jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 May 2003

Volume 93, Issue 10, pp. 5855-8792

Return to All Sections
back to top
RSS Feeds

Dependence of exchange coupling on NiO grain size in NiO/NiFe bilayers

Chung-Hee Nam, B. K. Cho, and Seonghoon Lee

J. Appl. Phys. 93, 6584 (2003); http://dx.doi.org/10.1063/1.1555321 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The texture and grain-size effects on the exchange bias in sputtered polycrystalline NiO/NiFe bilayers were studied. Two oriented antiferromagnetic NiO layers along (111) and (200) planes were fabricated on SiO2/Si(100) substrates by varying the Ar/O2 ratio. An exchange anisotropy field Hex was detected in both NiO/NiFe bilayers with a NiO(111) plane where Ni moments are in ferromagnetic (FM) order, and with a NiO(200) plane where Ni moments are in fully compensated antiferromagnetic (AF) order. In order to clarify the presence of the Hex in a NiO(200)/NiFe bilayer, we prepared NiO(200) layers with different grain sizes by controlling a total pressure at a constant Ar/O2 ratio in a sputter chamber. We observed that the Hex of the bilayer films with small grains of NiO(200) is larger than the Hex with large grains. This observation is consistent with a model that the exchange interaction is caused by the reorientation of the moments with AF layer spins rotating, rather than FM layer spins rotating at the interface of the bilayer. © 2003 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Et Exchange and superexchange interactions
75.30.Gw Magnetic anisotropy
68.55.-a Thin film structure and morphology
75.50.Ee Antiferromagnetics
75.50.Bb Fe and its alloys

Exchange bias in Co/Co3O4 bilayers

Biao You, Yixing Wang, Yanling Zhao, Liang Sun, Wenting Sheng, Minghu Pan, Jun Du, An Hu, and Mu Lu

J. Appl. Phys. 93, 6587 (2003); http://dx.doi.org/10.1063/1.1543878 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Exchange biasing effect in Co/Co3O4(t) bilayers was carefully investigated by a vibrating sample magnetometer. It was surprising that a significant exchange bias effect appeared when the temperature varied from 90 to 220 K. In this temperature range bulk Co3O4 should be in a paramagnetic state because its Néel temperature is about 40 K. The exchange bias field (HE) of Co/Co3O4 fluctuated in the range of 110–130 Oe with various thickness of Co3O4 at 90 K and HE was zero when the temperature was above 220 K. X-ray photoelectron spectroscopy results indicated that a thin CoO layer formed near the interface, which may be due to the interdiffusion between Co and Co3O4 layers. Therefore, the exchange bias effect in Co/Co3O4 bilayers is thought to be dominated by the exchange coupling between the Co and CoO layers. Using the finite-size effect theory, we evaluated the average thickness of interfacial CoO layer to be 39 Å. The fluctuation of HE in Co/Co3O4 is probably due to thickness fluctuations of the CoO. Assuming that HE is inversely proportional to the thickness of CoO, we can conclude that the approximate thickness range of CoO is from 36 to 43 Å. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.50.Ee Antiferromagnetics
75.50.Cc Other ferromagnetic metals and alloys
79.60.Jv Interfaces; heterostructures; nanostructures
68.35.Fx Diffusion; interface formation

Structural and magnetic characterization of ion-beam deposited NiFe/NixFe1−xO composite films

K.-W. Lin, R. J. Gambino, and L. H. Lewis

J. Appl. Phys. 93, 6590 (2003); http://dx.doi.org/10.1063/1.1543879 (3 pages) | Cited 10 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanocomposite films of Ni80Fe20/NixFe1−xO were prepared by a dual ion-beam deposition technique. The structural and magnetic properties of nanocomposite films fabricated with oxygen content in the deposition assist beam ranging from 0% to 55% were studied. The dependence of the resistivity on oxygen percent shows that the compositions with exchange-enhanced coercivity are close to a percolation threshold. A strong temperature dependence of coercivity Hc and exchange bias field Hex is found in these composite films. Films prepared with 46% O2 in the assist beam exhibit an enhanced Hc relative to Permalloy (Ni80Fe20) and a characteristic shifted hysteresis loop indicative of exchange coupling between the constituent metal and oxide phases. At T=10 K, films prepared with 44% O2 in the assist beam have an exchange shift Hex∼−225 Oe with a blocking temperature TB∼100 K that reflects the low Néel temperatures of FeO-rich NixFe1−xO solid solutions. © 2003 American Institute of Physics.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.50.Tt Fine-particle systems; nanocrystalline materials
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Et Exchange and superexchange interactions
68.55.-a Thin film structure and morphology
73.61.-r Electrical properties of specific thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Control of exchange bias by diluting the antiferromagnetic layer

A. Misra, U. Nowak, and K. D. Usadel

J. Appl. Phys. 93, 6593 (2003); http://dx.doi.org/10.1063/1.1543880 (3 pages) | Cited 11 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The domain state model for exchange bias is used for an investigation of recent experiments where the magnitude and direction of the exchange bias was controlled by He ion irradiation of an FeNi/FeMn sample. The defects in the sample which result from the irradiation are modeled as diluting the antiferromagnet (AFM) after the initial cooling procedure. This late dilution, carried out in presence of a field, leads to a rearrangement of the original domain structure of the AFM resulting in an enhancement or reduction in the bias field. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.50.Bb Fe and its alloys
75.50.Ee Antiferromagnetics
61.80.Jh Ion radiation effects
61.82.Bg Metals and alloys
75.70.Kw Domain structure (including magnetic bubbles and vortices)

Reversing exchange fields in CoFe/PtMn and CoFe/IrMn bilayers by carbon field irradiation

C. H. Yang, Chih-Huang Lai, and S. Mao

J. Appl. Phys. 93, 6596 (2003); http://dx.doi.org/10.1063/1.1557231 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
C-ion irradiation was performed in CoFe/PtMn and CoFe/IrMn systems with an applied field during irradiation to investigate the effects of the energy transfer between C ions and antiferromagnetic atoms (AF) on the exchange field Hex. The irradiated CoFe/PtMn samples showed reduced exchange fields and coercivity, which was attributed to the lattice distortion of PtMn. When samples were irradiated with an applied field antiparallel to the original exchange-bias direction, a partially reversed Hex was found in CoFe/PtMn, while a fully reversed Hex in CoFe/IrMn was observed at the dose of 2×1014 ions/cm2. Rapid energy transfer and temperature increase, originating from the interaction between C ions and AF atoms, resulted in spin reversal and formation of reversed AF domains when samples were irradiated in antiparallel fields. In addition, the thermal relaxation of Hex in CoFe/IrMn was suppressed by ion irradiation. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.60.Jk Magnetization reversal mechanisms
61.80.Jh Ion radiation effects
75.50.Bb Fe and its alloys
75.50.Ee Antiferromagnetics
61.82.Bg Metals and alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.30.Wx Spin crossover
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)

Exchange anisotropy of (001) oriented Mn1−xPtx/NiFe epitaxial films

T. Kume, Y. Sugiyama, T. Kato, S. Iwata, and S. Tsunashima

J. Appl. Phys. 93, 6599 (2003); http://dx.doi.org/10.1063/1.1558195 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Exchange anisotropy was investigated for Mn1−xPtx (x=0.06–0.40)/NiFe bilayers prepared by molecular-beam epitaxy on MgO (001) substrates. The bilayers exhibited a large exchange bias field without postannealing, which showed a maximum value of 140–160 Oe around x=0.11. This result is almost the same as those for the (111) oriented bilayers. The exchange anisotropy is induced with the easy direction parallel to the 〈110〉 axes in spite of the fact that the magnetic field is applied along the 〈100〉 direction during the deposition. Diffraction peaks from an ordered phase of Mn3Pt alloy were not observed in the reciprocal space map measured by x-ray diffraction. The origin of the exchange anisotropy is attributed to the antiferromagnetic spin arrangements of the MnPt layer with a disordered face-centered-cubic structure. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
75.30.Et Exchange and superexchange interactions
75.50.Ee Antiferromagnetics
75.50.Bb Fe and its alloys
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
68.55.-a Thin film structure and morphology

Mn diffusion effect in the exchange biased NiFe/FeMn/NiFe trilayers

S. W. Kim, J. K. Kim, J. H. Kim, B. K. Kim, J. Y. Lee, S. S. Lee, D. G. Hwang, and J. R. Rhee

J. Appl. Phys. 93, 6602 (2003); http://dx.doi.org/10.1063/1.1557238 (3 pages) | Cited 8 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated NiFe/Mn/FeMn/Mn/NiFe multilayers using ultrahigh vacuum ion-beam deposition system to study the diffusion effect of the inserted Mn on exchange biasing. As the thickness of the Mn layer was changed from 0 to 1.5 nm, the exchange biasing field Hex(top) at the top interface of FeMn/Mn/NiFe was decreased from 258 Oe to 24 Oe. On the other hand, the Hex(bottom) was slightly decreased 103 Oe to 78 Oe without a change in the coercive field Hc. Above 1.2 nm, a reverse phenomena of Hex was observed. After annealing at 200 °C, the Hex(top) was increased by almost a factor of 2; however, the Hex(bottom) did not change. The analyses of x-ray patterns and Auger spectroscopy showed that the abnormal tendency of Hex(bottom) originated from the diffusion of Mn atoms at bottom interface into the FeMn layer during film growth, and that the Mn was concentrated at the interface by annealing. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Bb Fe and its alloys
75.30.Et Exchange and superexchange interactions
68.35.Fx Diffusion; interface formation
75.50.Ee Antiferromagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Effects of in situ magnetic field application and postdeposition magnetic annealing on sputtered Ni80Fe20/Fe50Mn50/Ni80Fe20 trilayers

F. H. Chen, V. Ng, and A. O. Adeyeye

J. Appl. Phys. 93, 6605 (2003); http://dx.doi.org/10.1063/1.1557243 (3 pages) | Cited 3 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of in situ magnetic field deposition and postdeposition magnetic annealing on the exchange field and coercivity of Ni80Fe20/Fe50Mn50/Ni80Fe20 trilayers were investigated. Hysteresis loops reveal a one-sided plateau for unannealed samples, A clean loop without plateau was observed for samples annealed at 230 °C for 15 min in vacuum with an external magnetic field. An increase in coercivity was also observed. This can be attributed to the formation of NiFeMn alloy at the interfaces caused by annealing. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Nt Magnetic annealing and temperature-hysteresis effects
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.65.Ac Multilayers
81.15.Cd Deposition by sputtering
75.30.Et Exchange and superexchange interactions
68.35.Fx Diffusion; interface formation
75.50.Bb Fe and its alloys
75.50.Ee Antiferromagnetics

Properties of thin IrMn in exchange biased multilayers

J. C. Eckert, N. P. Stern, D. S. Snowden, P. D. Sparks, and M. J. Carey

J. Appl. Phys. 93, 6608 (2003); http://dx.doi.org/10.1063/1.1555331 (3 pages) | Cited 5 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report striking behavior in thin IrMn exchange-biased heterostructures. We have studied exchange-biased multilayers with IrMn thicknesses from 2 to 80 Å with 50-Å Ti over- and underlayers. The resistance of spin valves with Si/50-Å Ti/40-Å NiFe/8-Å Co/30-Å Cu/30-Å Co/tIrMn/50-Å Ti as a function of temperature shows anomalous behavior for 12 Å<tIrMn<26 Å. These features are not seen for spin valves in which the ferromagnetic layers are replaced with CoFe. To isolate the effects of the IrMn, resistance and magnetization versus temperature for structures of 50 Å Ti/ tIrMn /50 Å Ti were measured. Our measurements are suggestive of a model involving a mixed hcp/fcc phase of IrMn, in which the hcp phase undergoes a magnetic phase transition, and the resistance is influenced by a combination of the magnetic transition and the structural properties of the IrMn layer. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
75.30.Et Exchange and superexchange interactions
75.47.Np Metals and alloys
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.50.Ee Antiferromagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Co layer thickness dependence of exchange biasing for IrMn/Co and FeMn/Co

K. A. Seu, H. Huang, J. F. Lesoine, H. D. Showman, W. F. Egelhoff, L. Gan, and A. C. Reilly

J. Appl. Phys. 93, 6611 (2003); http://dx.doi.org/10.1063/1.1555332 (3 pages) | Cited 7 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a high resolution study of the ferromagnetic layer thickness dependence of exchange bias field (HEB) and coercivity (HC) in IrMn/Co and FeMn/Co bilayers using the magneto-optical Kerr effect. Samples are sputtered wedges on silicon with Co thicknesses ranging from 1 to 17 nm. The IrMn/Co (with exchange bias interface energy of ∼0.14 erg/cm2) shows square loops, a smooth increase in HEB with inverse thickness, and a complicated behavior for coercivity, perhaps due to competition with thickness dependent coercive mechanisms. The FeMn/Co (with exchange bias interface energy of ∼0.059 erg/cm2) shows more rounded loops, a plateau of HEB with decreasing thickness, and a smooth increase in coercivity with inverse thickness. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
78.20.Ls Magneto-optical effects
75.50.Cc Other ferromagnetic metals and alloys
75.50.Ee Antiferromagnetics
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.66.Bz Metals and metallic alloys

Abnormal temperature dependence of exchange bias in the NiFe5/Ta0.2/IrMn8 system

Kebin Li, Zaibing Guo, Guchang Han, Jinjun Qiu, and Yihong Wu

J. Appl. Phys. 93, 6614 (2003); http://dx.doi.org/10.1063/1.1555333 (3 pages) | Cited 2 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Exchange bias (Hex) between NiFe and IrMn across a spacer layer such as Ru, Cr, Cu, and Ta has been studied. Hex is almost destroyed when a 0.2-nm-thick Ta layer is inserted between NiFe and IrMn. Abnormal temperature (T) dependence of Hex (there is two magnetization hysteresis loops with different blocking temperatures; the T dependence is neither linear nor nature of Fermi-Dirac statistics, it is an exponential decay function) has been observed in the NiFe/Ta/IrMn system. The abnormal hysteresis loops are associated with two antiferromagnetic (AFM) phases formed due to interface diffusion after magnetic annealing. The exponential decay Hex with temperature is due to complicated coupling mechanisms involved in the system. It is suggested that the strength of the exchange bias should be the nature of long-range interaction while the blocking temperature of the system should be mainly determined by the structure of the FM/AFM interface. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.50.Ee Antiferromagnetics
75.60.Nt Magnetic annealing and temperature-hysteresis effects
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.35.Fx Diffusion; interface formation
66.30.Ny Chemical interdiffusion; diffusion barriers
75.50.Bb Fe and its alloys
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close