Non-linear interplay between exchange-bias-induced unidirectional anisotropy and oblique-deposition-induced uniaxial anisotropy

2013 ◽  
Vol 114 (4) ◽  
pp. 043911 ◽  
Author(s):  
Nguyen N. Phuoc ◽  
C. K. Ong
Keyword(s):  
Exchange Bias ◽  
Uniaxial Anisotropy ◽  
Non Linear ◽  
Unidirectional Anisotropy ◽  
Oblique Deposition

scholarly journals Voltage control of unidirectional anisotropy in ferromagnet-multiferroic system

2018 ◽  
Vol 4 (11) ◽  
pp. eaat4229 ◽  
Author(s):  
Sasikanth Manipatruni ◽  
Dmitri E. Nikonov ◽  
Chia-Ching Lin ◽  
Bhagwati Prasad ◽  
Yen-Lin Huang ◽  
...  
Keyword(s):  
Electric Field ◽  
Exchange Bias ◽  
Room Temperature ◽  
Uniaxial Anisotropy ◽  
Complementary Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
State Variables ◽  
Ultralow Energy ◽  
Unidirectional Anisotropy ◽  
Beyond Cmos

Demonstration of ultralow energy switching mechanisms is imperative for continued improvements in computing devices. Ferroelectric (FE) and multiferroic (MF) order and their manipulation promise an ideal combination of state variables to reach attojoule range for logic and memory (i.e., ~30× lower switching energy than nanoelectronics). In BiFeO3(BFO), the coupling between the antiferromagnetic (AFM) and FE order is robust at room temperature, scalable in voltage, stabilized by the FE order, and can be integrated into a fabrication process for a beyond-CMOS (complementary metal-oxide semiconductor) era. The presence of the AFM order and a canted magnetic moment in this system causes exchange interaction with a ferromagnet such as Co0.9Fe0.1or La0.7Sr0.3MnO3. Previous research has shown that exchange coupling (uniaxial anisotropy) can be controlled with an electric field. However, voltage modulation of unidirectional anisotropy, which is preferred for logic and memory technologies, has not yet been demonstrated. Here, we present evidence for electric field control of exchange bias of laterally scaled spin valves that is exchange coupled to BFO at room temperature. We show that the exchange bias in this bilayer is robust, electrically controlled, and reversible. We anticipate that magnetoelectricity at these scaled dimensions provides a powerful pathway for computing beyond modern nanoelectronics by enabling a new class of nonvolatile, ultralow energy computing elements.

scholarly journals Exchange-bias and magnetic anisotropy fields in core–shell ferrite nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. G. Silva ◽  
J. Depeyrot ◽  
Yu. L. Raikher ◽  
V. I. Stepanov ◽  
I. S. Poperechny ◽  
...  
Keyword(s):  
Spin Glass ◽  
Magnetic Moment ◽  
Exchange Bias ◽  
Uniaxial Anisotropy ◽  
Thermal Fluctuations ◽  
High Amplitude ◽  
Spin Coupling ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

AbstractExchange bias properties of MnFe$$_2$$ 2 O$$_4$$ 4 @$$\gamma$$ γ –Fe$$_2$$ 2 O$$_3$$ 3 core–shell nanoparticles are investigated. The measured field and temperature dependencies of the magnetization point out a well-ordered ferrimagnetic core surrounded by a layer with spin glass-like arrangement. Quasi-static SQUID magnetization measurements are presented along with high-amplitude pulse ones and are cross-analyzed by comparison against ferromagnetic resonance experiments at 9 GHz. These measurements allow one to discern three types of magnetic anisotropies affecting the dynamics of the magnetic moment of the well-ordered ferrimagnetic NP’s core viz. the easy-axis (uniaxial) anisotropy, the unidirectional exchange-bias anisotropy and the rotatable anisotropy. The uniaxial anisotropy originates from the structural core–shell interface. The unidirectional exchange-bias anisotropy is associated with the spin-coupling at the ferrimagnetic/spin glass-like interface; it is observable only at low temperatures after a field-cooling process. The rotatable anisotropy is caused by partially-pinned spins at the core/shell interface; it manifests itself as an intrinsic field always parallel to the external applied magnetic field. The whole set of experimental results is interpreted in the framework of superparamagnetic theory, i.e., essentially taking into account the effect of thermal fluctuations on the magnetic moment of the particle core. In particular, it is found that the rotatable anisotropy of our system is of a uniaxial type.

Interplay between exchange bias and uniaxial anisotropy in a ferromagnetic/antiferromagnetic exchange-coupled system

2005 ◽  
Vol 71 (21) ◽  
Author(s):  
S. H. Chung ◽  
A. Hoffmann ◽  
M. Grimsditch
Keyword(s):  
Exchange Bias ◽  
Uniaxial Anisotropy ◽  
Coupled System ◽  
Antiferromagnetic Exchange

Exchange Bias in Co/FeMn and Co/IrMn Structures Induced by Deposition in Presence of Magnetic Field

2012 ◽  
Vol 190 ◽  
pp. 93-96
Author(s):  
I.O. Dzhun ◽  
N.G. Chechenin ◽  
S.A. Dushenko ◽  
E.A. Konstantinova
Keyword(s):  
Magnetic Field ◽  
Angular Dependence ◽  
Exchange Bias ◽  
Low Temperatures ◽  
Resonance Field ◽  
Blocking Temperature ◽  
Bilayer Structure ◽  
Magnetron Deposition ◽  
Unidirectional Anisotropy ◽  
Antiferromagnetic Layer

By measuring the angular dependence of ferromagnetic resonance field at room and low temperatures, it is demonstrated that the magnitude of magnetic field applied during magnetron deposition of Ta/F/AF/Ta structures, where F=Co, NiFe and AF=FeMn and IrMn, influences the uniaxial and unidirectional anisotropy, magnetization and the exchange bias blocking temperature. The deposition field effects on the bilayer structure are compared with the effects on a similar structure, but without antiferromagnetic layer. The exchange bias blocking temperature of investigated structures is found to be significantly lower than the Néel temperature of a bulk antiferromagnet. The origin of the observed effects is shortly discussed.

Observation of giant exchange bias effect in Ni-Mn-Ti all-d-metal Heusler alloy

2021 ◽  
Author(s):  
Saheli Samanta ◽  
Subrata Ghosh ◽  
Kalyan Mandal
Keyword(s):  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Relaxation ◽  
Training Effect ◽  
Magnetic Memory ◽  
Relaxation Processes ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Intrinsic Nature ◽  
Unidirectional Anisotropy

Abstract We report a giant exchange bias (EB) field of about 3.68 KOe during field cooled process in all-d-metal Ni40(FeCo)4Mn36Ti20 Heusler alloy. The study of magnetic memory effect and isothermal magnetic relaxation processes suggest that the giant EB field arises due to the possible coexistence of antiferromagnetic (AFM) and ferromagnetic (FM) phase exchange interaction in the studied system at temperatures below 35 K. Furthermore, the temperature and cooling field dependence of EB effect are analyzed which are related to the change in unidirectional anisotropy at FM/AFM interface. The study of a well-established training effect confirms the intrinsic nature of the observed EB behavior. This result will open up a new way towards the development of EB materials considering all-d-metal Heusler alloy systems.

Large Uniaxial Anisotropy Induced in Soft Ferromagnetic Thin Films by Oblique Deposition of Underlayer

2018 ◽  
Vol 9 ◽  
pp. 1-5
Author(s):  
Rakesh K. Singh ◽  
Nicholas D. Rizzo ◽  
Ashwin Boochakravarthy ◽  
Nathan Newman
Keyword(s):  
Thin Films ◽  
Uniaxial Anisotropy ◽  
Ferromagnetic Thin Films ◽  
Soft Ferromagnetic ◽  
Oblique Deposition

Spin Glassiness and Ferromagnetism in Disordered Ni-Mn Alloys

1982 ◽  
Vol 19 ◽  
Author(s):  
James S. Kouvel
Keyword(s):  
Spin Glass ◽  
Critical Field ◽  
Curie Point ◽  
Magnetic Measurements ◽  
Spontaneous Magnetization ◽  
Uniaxial Anisotropy ◽  
Hysteresis Loops ◽  
Initial Susceptibility ◽  
Unidirectional Anisotropy ◽  
Glass Properties

ABSTRACTFrom magnetic measurements, the alloy Ni78Mn22 is found to undergo a field-induced transition from spin glassiness to ferromagnetism at a critical field that decreases from ∼140 Oe to zero as the temperature is raised from 4.2 K to 40 K, the ferromagnetic Curie point being ∼270 K. The alloy Ni74Mn26 is found to transform at 80 K from a spin glass to a state of infinite initial susceptibility but no spontaneous magnetization and to remain so up to 155 K, where it becomes paramagnetic. The spin-glass properties of Ni78Mn22 below 40 K and of Ni74Mn26 below 80 K include displaced hysteresis loops produced by cooling in a field. The changes in the hysteresis loops upon subsequent warming correspond to a gradual conversion of a unidirectional anisotropy to a uniaxial anisotropy.

Enhancing exchange bias and tailoring microwave properties of FeCo/MnIr multilayers by oblique deposition

2012 ◽  
Vol 112 (11) ◽  
pp. 113908 ◽  
Author(s):  
Nguyen N. Phuoc ◽  
Guozhi Chai ◽  
C. K. Ong
Keyword(s):  
Exchange Bias ◽  
Microwave Properties ◽  
Oblique Deposition

Temperature dependence of exchange bias and training effect in Co/CoO film with induced uniaxial anisotropy

2015 ◽  
Vol 48 (27) ◽  
pp. 275002 ◽  
Author(s):  
R Wu ◽  
J B Fu ◽  
D Zhou ◽  
S L Ding ◽  
J Z Wei ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Exchange Bias ◽  
Uniaxial Anisotropy ◽  
Training Effect ◽  
And Training
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