Exchange bias and anomalous vertical shift of the hysteresis loops in milled Fe/MnO2 material

2006 ◽  
Vol 299 (1) ◽  
pp. 11-20 ◽  
Author(s):  
E.C. Passamani ◽  
C. Larica ◽  
C. Marques ◽  
J.R. Proveti ◽  
A.Y. Takeuchi ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Hysteresis Loops ◽  
Vertical Shift

scholarly journals Structural, electronic and magnetic properties of YMnO3/La0.7Sr0.3MnO3heterostructures

2014 ◽  
Vol 47 (3) ◽  
pp. 1054-1064 ◽  
Author(s):  
Amitesh Paul ◽  
Carlos Zandalazini ◽  
Pablo Esquinazi ◽  
Carmine Autieri ◽  
Biplab Sanyal ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Hysteresis Loops ◽  
Magnetic Interactions ◽  
Ferromagnetic Phase ◽  
High Coercivity ◽  
Vertical Shift ◽  
Intrinsic Nature ◽  
Lattice Constants ◽  
Horizontal Shift ◽  
Magnetization Axis

Heterostructures with competing magnetic interactions are often exploited for their tailored new functionalities. Exchange bias is one such outcome of interfacial coupling across ferromagnetic–antiferromagnetic, multiferroic–ferromagnetic, two antiferromagnetic, or antiferromagnetic and paramagnetic interfaces. Apart from the usual horizontal shift of the hysteresis loop (exchange bias shift), a small `vertical shift' of the hysteresis loops along the magnetization axis has also been seen, but it was always relatively small. Recently, an unusually large `vertical shift' in epitaxial bilayer heterostructures comprising ferromagnetic La0.7Sr0.3MnO3and multiferroic orthorhombic YMnO3layers was reported. Here, using polarized neutron reflectometry, the magnetic proximity effect in such bilayers has been investigated. A detailed magnetic depth profile at the interface, elucidating the intrinsic nature of the vertical shift in such heterostructures, is reported. Further corroboration of this observation has been made by means of first-principles calculations, and the structural and electronic properties of YMnO3/La0.7Sr0.3MnO3heterostructures are studied. Although in the bulk, the ground state of YMnO3is anE-type antiferromagnet, the YMnO3/La0.7Sr0.3MnO3heterostructure stabilizes the ferromagnetic phase in YMnO3in the interface region. It is found that, in the hypothetical ferromagnetic phase of bulk YMnO3, the polarization is suppressed, and owing to a large difference between the lattice constants in theabplane a strong magnetocrystalline anisotropy is present. This anisotropy produces a high coercivity of the unusual ferromagnetic YMnO3phase at the interface, which is responsible for the large vertical shift observed in experiment.

Exchange Bias in CrO2/Cr2O3 Bilayer Thin Films

2006 ◽  
Vol 45 ◽  
pp. 2528-2533 ◽  
Author(s):  
S. Srinath ◽  
N.A. Frey ◽  
H. Srikanth ◽  
G.X. Miao ◽  
A. Gupta
Keyword(s):  
Thin Films ◽  
Magnetic Anisotropy ◽  
Variable Thickness ◽  
Exchange Bias ◽  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Anisotropy Constant ◽  
Effective Magnetic Anisotropy ◽  
Large Anisotropy

We have investigated the exchange bias in CVD grown epitaxial CrO2/Cr2O3 bilayer thin films using hysteresis loops and resonant RF transverse susceptibility. M-H loops indicated an enhanced coercivity without appreciable loop shift and the transverse susceptibility in CrO2/Cr2O3 bilayers revealed features associated with both the ferromagnetic and antiferromagnetic phases. In addition, TS yielded large anisotropy constant (Keff) values depending on the fraction of Cr2O3 present. The large anisotropy fields observed cannot be accounted for by the variable thickness of CrO2 alone and are indicative of possible exchange coupling between CrO2 and Cr2O3 phases that significantly affects the effective magnetic anisotropy.

Exchange Bias Properties in Bulk Ni45Co5Mn38Sn12 Heusler Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 272-276 ◽  
Author(s):  
Chao Jing ◽  
Ye Jun Yang ◽  
Dong Hua Yu ◽  
Zhe Li ◽  
Xiao Long Wang ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Magnetic Hysteresis Loop ◽  
Zero Field ◽  
Co Substitution ◽  
Exchange Bias Field

We report the exchange bias properties in the bulk Ni45Co5Mn38Sn12quaternary Heusler alloy. The ferromagnetic (FM) –antiferromagnetic (AFM) interactions get reinforced after the Co substitution for Ni in the Ni-Mn-Sn alloy, which increase the exchange bias field (HE). A maximum shift in hysteresis loops of 306 Oe was observed in the 10 kOe field cooled sample. The origin of this large exchange bias field has been discussed. Magnetic hysteresis loop obtained in the zero field cooled (ZFC) mode shows double-shifted loop, and the reason of this phenomenon has been explained in detail.

scholarly journals Exchange bias in ferromagnetic bilayers with orthogonal anisotropies: the case of GaMnAsP/GaMnAs combination

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Suho Choi ◽  
Seul-Ki Bac ◽  
Xinyu Liu ◽  
Sanghoon Lee ◽  
Sining Dong ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Easy Axis ◽  
Initial Conditions ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
The Other ◽  
Planar Hall Effect ◽  
Magnetic Layers ◽  
Out Of Plane ◽  
Magnetic Hysteresis Loops

Abstract We report the observation of exchange bias in a ferromagnetic Ga0.94Mn0.06As0.77P0.23/ Ga0.94Mn0.06As bilayer, in which the easy axis in one layer is oriented out-of-plane, and in the other in-plane. Magnetization reversal in this system is explored using planar Hall effect (PHE) measurements under various initial conditions and with various field-cooling orientations. Our results show that the two magnetic layers are ferromagnetically exchange-coupled, and that such coupling results in pronounced exchange-bias-like shifts of magnetic hysteresis loops during reversal of in-plane magnetization. The presence of exchange bias in this system can be understood on the basis of magnetic closure domains formed in the layer with the out-of-plane easy axis.

scholarly journals Origins of the Exchange-Bias Phenomenology, Coercivity Enhancement, and Asymmetric Hysteretic Shearing in Core-Surface Smart Nanoparticles

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Rıza Erdem ◽  
Orhan Yalçın ◽  
Songül Özüm ◽  
Nazire Çiftçi
Keyword(s):  
Particle Size ◽  
Ising Model ◽  
Exchange Bias ◽  
Strong Dependence ◽  
Hysteresis Loops ◽  
Pair Approximation ◽  
Core Surface ◽  
Model Hamiltonian ◽  
Interaction Term ◽  
Experimental Findings

We have used a spin-1 Ising model Hamiltonian with dipolar (bilinear,J), quadrupolar (biquadratic,K), and dipolar-quadrupolar (odd,L) interactions in pair approximation to investigate the exchange-bias (EB), coercive field, and asymmetric hysteretic shearing properties peculiar to core/surface (C/S) composite nanoparticles (NPs). Shifted hysteresis loops with an asymmetry and coercivity enhancement are observed only in the presence of the odd interaction term in the Hamiltonian expression and their magnitudes show strong dependence on the value ofL. The observed coercivity and EB inC/SNPs originated from nonzero odd coupling energies and their dependence on temperature (T) and particle size (R) are also discussed in relation to experimental findings.

scholarly journals A simple lattice model for hysteresis loops with exchange bias

2004 ◽  
Vol 272-276 ◽  
pp. 703-704 ◽  
Author(s):  
Eduard Vives ◽  
Xavier Illa ◽  
Antoni Planes
Keyword(s):  
Lattice Model ◽  
Exchange Bias ◽  
Hysteresis Loops ◽  
Simple Lattice

scholarly journals Effect of Magnetic Field and Temperature on the Exchange Bias in Phase-Separated Nd1-xSrxCoO3(x=0.10, 0.15)

2015 ◽  
Vol 9 (1) ◽  
pp. 56-59 ◽  
Author(s):  
Yi-Yun Yang
Keyword(s):  
Magnetic Field ◽  
Exchange Bias ◽  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Freezing Temperature ◽  
Solid State Reaction Method ◽  
Conventional Solid State Reaction ◽  
Magnetic Field Axis ◽  
Coexisting Phases ◽  
The Magnetic Field

The exchange bias phenomena of phase-separated Nd1-xSrxCoO3(x=0.10, 0.15) samples were systematically investigated in this paper. The samples were prepared using conventional solid state reaction method. When the NdSrCoO samples cooled down in magnetic field below freezing temperature, the hysteresis loops shifted along the magnetic field axis. Moreover, exchange bias of Nd1-xSrxCoO3 is strongly dependent on the field and the temperature. The influence of magnetic field on the relative ratio of the coexisting phases may be responsible for these behaviors. Therefore, our study confirmed that in phase-separated system, the exchange coupling at the interface between the ferromagnetism clusters and the spin glass regions may induce interfacial exchange anisotropy.

scholarly journals Ferromagnetic excess moments and apparent exchange bias in FeF2 single crystals

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
D. C. Joshi ◽  
P. Nordblad ◽  
R. Mathieu
Keyword(s):  
Low Temperature ◽  
Single Crystals ◽  
Exchange Bias ◽  
Hysteresis Loops ◽  
Temperature Hysteresis ◽  
Remnant Magnetization ◽  
Antiferromagnetic Structure ◽  
Antiferromagnetic Layer

AbstractThe anisotropic antiferromagnet FeF2 has been extensively used as an antiferromagnetic layer to induce exchange bias effects in ferromagnetic/antiferromagnetic bilayers and heterostructures. In this work, an apparent exchange bias occurring in the low temperature hysteresis loops of FeF2 single crystals is investigated. A detailed investigation of the hysteresis and remnant magnetization indicates that the observation of an apparent exchange bias in FeF2 stems from an intrinsic excess moment associated with a distortion of the antiferromagnetic structure of piezomagnetic origin.

Oscillatory Angular Dependence of Exchange Bias for Epitaxial NiO-Co (001) Bilayers

2001 ◽  
Vol 674 ◽  
Author(s):  
S. Dubourg ◽  
J.F. Bobo ◽  
B. Warot ◽  
E. Snoeck ◽  
J.C. Ousset
Keyword(s):  
Magnetic Field ◽  
Exchange Bias ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Field Application ◽  
Zero Field ◽  
Sign Change ◽  
Realistic Description ◽  
Sputter Deposited ◽  
The Magnetic Field

ABSTRACTWe have sputter-deposited NiO-Co bilayers on MgO (001) substrates. NiO grows epitaxially on MgO at 900°C and subsequently the room deposited 80 Åthick Co films have a fcc crystal structure in epitaxy with the oxide underlayer. These samples were warmed up to 300° C and then zero-field or field cooled through the NiO Néel temperature (a 300 Oe magnetic field was applied along the [100] or the [110] MgO axis). Magnetic hysteresis loops were obtained by magneto-optical Kerr effect, the magnetic field being oriented in the plane of the substrate for various angles α with respect to the [100] direction. The usually expected behavior for such experiments is a smooth angular α dependence of the exchange bias HE close to a cosine with only one sign change over 180°. The high crystallographic coherence of our NiO/Co bilayers induces a very unusual oscillatory HE (α) dependence with several sign changes according to the NiO axis field application. Despite of the Co magnetization switching mechanism which is not a pure coherent rotation, we propose a Stoner-Wohlfhart model including four fold anisotropy and unidirectional exchange anisotropy giving a realistic description of these typical magnetic properties.

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