scholarly journals Correlation between Ferromagnetic Layer Easy Axis and the Tilt Angle of Self Assembled Chiral Molecules

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 6036
Author(s):  
Nir Sukenik ◽  
Francesco Tassinari ◽  
Shira Yochelis ◽  
Oded Millo ◽  
Lech Tomasz Baczewski ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Tilt Angle ◽  
Easy Axis ◽  
Ferromagnetic Layer ◽  
Clear Correlation ◽  
Chiral Molecules ◽  
Axis Direction ◽  
Out Of Plane ◽  
Magnetic Substrate

The spin–spin interactions between chiral molecules and ferromagnetic metals were found to be strongly affected by the chiral induced spin selectivity effect. Previous works unraveled two complementary phenomena: magnetization reorientation of ferromagnetic thin film upon adsorption of chiral molecules and different interaction rate of opposite enantiomers with a magnetic substrate. These phenomena were all observed when the easy axis of the ferromagnet was out of plane. In this work, the effects of the ferromagnetic easy axis direction, on both the chiral molecular monolayer tilt angle and the magnetization reorientation of the magnetic substrate, are studied using magnetic force microscopy. We have also studied the effect of an applied external magnetic field during the adsorption process. Our results show a clear correlation between the ferromagnetic layer easy axis direction and the tilt angle of the bonded molecules. This tilt angle was found to be larger for an in plane easy axis as compared to an out of plane easy axis. Adsorption under external magnetic field shows that magnetization reorientation occurs also after the adsorption event. These findings show that the interaction between chiral molecules and ferromagnetic layers stabilizes the magnetic reorientation, even after the adsorption, and strongly depends on the anisotropy of the magnetic substrate. This unique behavior is important for developing enantiomer separation techniques using magnetic substrates.

scholarly journals Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3

2021 ◽  
Author(s):  
Mahendra DC ◽  
Ding-Fu Shao ◽  
Vincent Hou ◽  
Patrick Quarterman ◽  
Ali Habiboglu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
External Magnetic Field ◽  
Spin Polarization ◽  
Density Functional ◽  
Ferromagnetic Layer ◽  
Magnetic Memory ◽  
Spin Orbit ◽  
Logic Devices ◽  
Out Of Plane

Abstract High spin-orbit torques (SOTs) generated by topological materials and heavy metals interfaced with a ferromagnetic layer show promise for next generation magnetic memory and logic devices. SOTs generated from the in-plane spin polarization along y-axis originated by the spin Hall and Edelstein effects can switch magnetization collinear with the spin polarization in the absence of external magnetic fields. However, an external magnetic field is required to switch the magnetization along x and z-axes via SOT generated by y-spin polarization. Here, we present that the above limitation can be circumvented by unconventional SOT in magnetron-sputtered thin film MnPd3. In addition to the conventional in-plane anti-damping-like torque due to the y-spin polarization, out-of-plane and in-plane anti-damping-like torques originating from z-spin and x-spin polarizations, respectively have been observed at room temperature. The spin torque efficiency (θ_y) corresponding to the y-spin polarization from MnPd3 thin films grown on thermally oxidized silicon substrate and post annealed at 400 ℃ is 0.34 - 0.44 while the spin conductivity (σ_zx^y) is ~ 5.70 – 7.30× 105 ℏ⁄2e Ω-1m-1. Remarkably, we have demonstrated complete external magnetic field-free switching of perpendicular Co layer via unconventional out-of-plane anti-damping-like torque from z-spin polarization. Based on the density functional theory calculations, we determine that the observed x- and z- spin polarizations with the in-plane charge current are due to the low symmetry of the (114) oriented MnPd3 thin films. Taken together, the new material reported here provides a path to realize a practical spin channel in ultrafast magnetic memory and logic devices.

scholarly journals Magnetization switching in ferromagnets by adsorbed chiral molecules without current or external magnetic field

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Oren Ben Dor ◽  
Shira Yochelis ◽  
Anna Radko ◽  
Kiran Vankayala ◽  
Eyal Capua ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Chiral Molecules ◽  
Magnetization Switching

scholarly journals Switching of perpendicularly polarized nanomagnets with spin orbit torque without an external magnetic field by engineering a tilted anisotropy

2015 ◽  
Vol 112 (33) ◽  
pp. 10310-10315 ◽  
Author(s):  
Long You ◽  
OukJae Lee ◽  
Debanjan Bhowmik ◽  
Dominic Labanowski ◽  
Jeongmin Hong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Data Storage ◽  
Easy Axis ◽  
Film Plane ◽  
The Other ◽  
Spin Orbit ◽  
Applied Current ◽  
Density Data ◽  
Magnetic Easy Axis

Spin orbit torque (SOT) provides an efficient way to significantly reduce the current required for switching nanomagnets. However, SOT generated by an in-plane current cannot deterministically switch a perpendicularly polarized magnet due to symmetry reasons. On the other hand, perpendicularly polarized magnets are preferred over in-plane magnets for high-density data storage applications due to their significantly larger thermal stability in ultrascaled dimensions. Here, we show that it is possible to switch a perpendicularly polarized magnet by SOT without needing an external magnetic field. This is accomplished by engineering an anisotropy in the magnets such that the magnetic easy axis slightly tilts away from the direction, normal to the film plane. Such a tilted anisotropy breaks the symmetry of the problem and makes it possible to switch the magnet deterministically. Using a simple Ta/CoFeB/MgO/Ta heterostructure, we demonstrate reversible switching of the magnetization by reversing the polarity of the applied current. This demonstration presents a previously unidentified approach for controlling nanomagnets with SOT.

scholarly journals Correlation of composition, aspect ratio and magnetic resistance of multilayer micro- and nanowires of the “ferromagnetic / diamagnetic” type

Doklady BGUIR ◽  
2021 ◽  
Vol 19 (2) ◽  
pp. 5-13
Author(s):  
V. M. Fedosyuk
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Aspect Ratio ◽  
Aluminum Oxide ◽  
Giant Magnetoresistance ◽  
Pore Diameter ◽  
Ferromagnetic Layer ◽  
Type I ◽  
Magnetic Layers ◽  
The Matrix

 The results of study of the giant magnetoresistance coefficient (GMR) in multilayer micro- and nanowires based on successively alternating ferromagnetic (Co, CoNi and NiFe) and diamagnetic (Cu) layers are presented in the paper. The samples were obtained by electrochemical deposition into the matrix pores. Aluminum oxide was used as matrices. To establish the influence of the aspect ratio, matrices of two types were used: with a pore diameter of 8 µm and 170–200 nm and a variable thickness from 10 to 60 µm. Investigations of the GMR coefficient were carried out by measuring the current-voltage characteristics in external magnetic fields up to 130 mT. When using type I matrices (pore diameter 8 μm), a positive GMR coefficient (an increase in electrical resistivity in an external magnetic field) was noted, while when using type II matrices (pore diameter 170–200 nm), a negative GMR coefficient was established (a decrease in electrical resistance in an external magnetic field). This is due to the enhancement of the interactions of spin-polarized electrons in the magnetic layers through the copper layer through the RKKY exchange with an increase in the aspect ratio. A significant effect of the composition of the ferromagnetic layer (Co, CoNi, and NiFe) on the value  of the GMR coefficient is noted. The maximum value of the negative GMR coefficient (up to –27.5 %) was established for the CoNi-based nanowire system. The use of multilayer micro- and nanowires, electrolytically deposited in a matrix of aluminum oxide with the ability to control the GMR coefficients, opens up perspective use of these objects as sensitive elements (sensors) of a constant magnetic field, as well as devices for storing magnetic information with a vertical principle. 

scholarly journals Interfacial ferromagnetism in a Co/CdTe ferromagnet/semiconductor quantum well hybrid structure

2018 ◽  
Vol 60 (8) ◽  
pp. 1566
Author(s):  
I.V. Kalitukha ◽  
M. Salewski ◽  
I.A. Akimov ◽  
V.L. Korenev ◽  
V.F. Sapega ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Quantum Well ◽  
Proximity Effect ◽  
Ferromagnetic Layer ◽  
Hybrid Structure ◽  
Magnetization Curves ◽  
Out Of Plane ◽  
Semiconductor Quantum Well ◽  
Magnetic Ions

AbstractThe magnetization properties of a ferromagnet-semiconductor Co/CdMgTe/CdTe quantum well hybrid structure are investigated by several techniques. Exploiting the proximity effect between acceptor bound holes and magnetic ions we detect the magnetization curves by measuring the circular polarization of photoluminescence in an out-of-plane magnetic field. We show that magnetization originates from interfacial ferromagnet on Co-CdMgTe interface and the proximity effect is caused by magnetization of interfacial Co-CdMgTe ferromagnetic layer whose magnetic properties are very different from Co.

scholarly journals Cluster magnetic octupole induced out-of-plane spin polarization in antiperovskite antiferromagnet

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yunfeng You ◽  
Hua Bai ◽  
Xiaoyu Feng ◽  
Xiaolong Fan ◽  
Lei Han ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Spin Polarization ◽  
Magnetic Layer ◽  
High Density ◽  
Spin Configuration ◽  
Spintronic Devices ◽  
Out Of Plane ◽  
Flow Through ◽  
New Perspective

AbstractOut-of-plane spin polarization σz has attracted increasing interests of researchers recently, due to its potential in high-density and low-power spintronic devices. Noncollinear antiferromagnet (AFM), which has unique 120° triangular spin configuration, has been discovered to possess σz. However, the physical origin of σz in noncollinear AFM is still not clear, and the external magnetic field-free switching of perpendicular magnetic layer using the corresponding σz has not been reported yet. Here, we use the cluster magnetic octupole in antiperovskite AFM Mn3SnN to demonstrate the generation of σz. σz is induced by the precession of carrier spins when currents flow through the cluster magnetic octupole, which also relies on the direction of the cluster magnetic octupole in conjunction with the applied current. With the aid of σz, current induced spin-orbit torque (SOT) switching of adjacent perpendicular ferromagnet is realized without external magnetic field. Our findings present a new perspective to the generation of out-of-plane spin polarizations via noncollinear AFM spin structure, and provide a potential path to realize ultrafast high-density applications.

QUALITATIVE COMPARISON OF THE THERMODYNAMICS OF Mn12-ac AND Fe8 MOLECULE MAGNETS FOR Dβ ~ 0.031

2011 ◽  
Vol 25 (15) ◽  
pp. 1281-1291
Author(s):  
M. T. THOMAZ ◽  
ONOFRE ROJAS ◽  
E. V. CORRÊA-SILVA
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Specific Heat ◽  
Excited States ◽  
Single Molecule ◽  
Easy Axis ◽  
Unexpected Result ◽  
Single Molecule Magnets ◽  
Qualitative Comparison ◽  
Percentage Difference

The magnetization and the specific heat of two single molecule magnets (SMM) with spin-10, Mn 12- ac and Fe 8, are compared for Dβ ~ 0.031. The rhombic term in the Fe 8 molecule makes the x-component of its magnetization to be larger than that of the Mn 12- ac molecule. The axial symmetry of the Mn 12- ac favors the z-component of its magnetization, in comparison to the Fe 8 molecule. For T ≳ 18 K, the specific heat of the Mn 12- ac is large (80%, at most) than that of the Fe 8, at the same temperature. The corrections from the S = 9 excited states of these SMM's do not invalidate our results. An unexpected result occurs when the angle between the easy-axis and the external magnetic field equals π/4: the aforementioned percentage difference of the specific heat reaches 3% for D β ≲ 0.025 and h/k ∈[1.93, 2.04], when they are compared at distinct temperatures [Formula: see text]. This small percentage difference also happens for the average specific heat of both SMM's at those temperatures and h/D Mn ∈ [1.97, 2.1].

Influence of Magnetic Anisotropy on Inverse Spin Hall Voltage

SPIN ◽  
2017 ◽  
Vol 07 (04) ◽  
pp. 1750007 ◽  
Author(s):  
M. Y. Song ◽  
G. Y. Luo ◽  
J. G. Lin ◽  
M. G. Samant ◽  
S. S. P. Parkin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Anisotropy ◽  
Ferromagnetic Resonance ◽  
Easy Axis ◽  
Hall Voltage ◽  
Spin Pumping ◽  
Pumping Efficiency ◽  
Effective Magnetization ◽  
The Magnetic Field

Spin pumping efficiency (SPE) in a ferromagnetic (FM)/Pt system relies on the effective magnetization damping of FM layer and the interface spin mixing conductance. However, there are very few studies on the influence of magnetic anisotropy of FM material on SPE. In this study, the spin pumping induced spin voltage [Formula: see text] in Fe3O4(58.9[Formula: see text]nm)/Pt(5.5[Formula: see text]nm) is investigated in two different orientations of the external magnetic field, one parallel and other perpendicular to the in-plane easy axis of Fe3O4. The value of [Formula: see text] with the magnetic field along the easy axis is 38% higher compared with that along the hard axis. The possible origin of this enhancement is investigated based on the model of ferromagnetic resonance induced spin pumping.

scholarly journals Superconducting magnetoresistance in ferromagnet/superconductor/ferromagnet trilayers

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
D. Stamopoulos ◽  
E. Aristomenopoulou
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Hybrid Nanostructures ◽  
Transport Mechanisms ◽  
Magnetic Domains ◽  
Structural Units ◽  
Extraordinary Magnetoresistance ◽  
Out Of Plane ◽  
Dipolar Fields ◽  
Macroscopic Parameters

Abstract Magnetoresistance is a multifaceted effect reflecting the diverse transport mechanisms exhibited by different kinds of plain materials and hybrid nanostructures; among other, giant, colossal and extraordinary magnetoresistance versions exist, with the notation indicative of the intensity. Here we report on the superconducting magnetoresistance observed in ferromagnet/superconductor/ferromagnet trilayers, namely Co/Nb/Co trilayers, subjected to a parallel external magnetic field equal to the coercive field. By manipulating the transverse stray dipolar fields that originate from the out-of-plane magnetic domains of the outer layers that develop at coercivity, we can suppress the supercurrent of the interlayer. We experimentally demonstrate a scaling of the magnetoresistance magnitude that we reproduce with a closed-form phenomenological formula that incorporates relevant macroscopic parameters and microscopic length scales of the superconducting and ferromagnetic structural units. The generic approach introduced here can be used to design novel cryogenic devices that completely switch the supercurrent ‘on’ and ‘off’, thus exhibiting the ultimate magnetoresistance magnitude 100% on a regular basis.

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