Superconducting magnetoresistance in ferromagnet/superconductor/ferromagnet trilayers

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

Nature Communications ◽

10.1038/s41467-021-26893-6 ◽

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.

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

Molecules ◽

10.3390/molecules25246036 ◽

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.

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A kinetic Monte Carlo study for stripe-like magnetic domains in ferrimagnetic thin films

Open Physics ◽

10.2478/s11534-013-0211-7 ◽

2013 ◽

Vol 11 (4) ◽

Cited By ~ 1

Author(s):

Botond Tyukodi ◽

Ioan-Augustin Chioar ◽

Zoltán Néda

Keyword(s):

Magnetic Field ◽

Monte Carlo ◽

External Magnetic Field ◽

Kinetic Monte Carlo ◽

Magnetic Domain ◽

Hysteresis Loops ◽

Monte Carlo Study ◽

Driving Frequency ◽

Magnetic Domains ◽

Equilibrium Limit

AbstractThe topology and dynamics of stripe-like magnetic domains obtained in a ferrimagnetic garnet subjected to a time-dependent external magnetic field is studied experimentally and theoretically. Experiments are performed on a commercially available magnetic bubble apparatus, allowing the observation of the time-evolution of the magnetic domain structure. The system is modeled by a meso-scale Ising-type lattice model. Exchange and dipolar interactions between the spins, and interaction of the spins with the external magnetic field are considered. The model is investigated by kinetic Monte Carlo simulations with time-varying transition rates. In the limit of low temperatures the elaborated model leads to a magnetic domain topology and dynamics that is similar to the ones observed in the experiments. In the highly non-equilibrium limit with a high driving frequency the model reproduces the experimentally recorded hysteresis loops as well.

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

10.21203/rs.3.rs-132828/v1 ◽

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.

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