Mikhail Erekhinsky

Control of spin injection by direct current in lateral spin valves

The spin injection and accumulation in metallic lateral spin valves with transparent interfaces are studied using dc injection current. Unlike ac-based techniques, this allows the investigation of the effects of the direction and magnitude of the injected current. We find that the spin accumulation is reversed by changing the direction of the injected current, whereas its magnitude does not change. The injection mechanism for both current directions is thus perfectly symmetric, leading to the same spin injection efficiency for both spin types. This result is accounted for by a spin-dependent diffusion model. Joule heating increases considerably the local temperature in the spin valves when high-current densities are injected (

Surface enhanced spin-flip scattering in lateral spin valves

\ensuremath{\sim}80\char21{}105\text{ }\text{K}

Spin-dependent Seebeck effect in non-local spin valve devices

for

Tuning exchange bias in Ni/FeF2 heterostructures using antidot arrays

1\char21{}2\ifmmode\times\else\texttimes\fi{}{10}^{7}\text{ }\text{A}\text{ }{\text{cm}}^{\ensuremath{-}2}

Exchange bias induced by the Fe3O4 Verwey transition

), strongly affecting the spin accumulation.

The fabrication of ordered arrays of exchange biased Ni/FeF2 nanostructures

We performed non-local electrical measurements of a series of Py/Cu lateral spin valve devices with different Cu thicknesses. We show that both the spin diffusion length of Cu and the apparent spin polarization of Py increase with Cu thickness. By fitting the results to a modified spin-diffusion model, we show that the spin diffusion length of Cu is dominated by spin-flip scattering at the surface. In addition, the dependence of spin polarization of Py on Cu thickness is due to a strong spin-flip scattering at the Py/Cu interface.Nonlocal transport in Py/Cu lateral spin valves shows that the Cu spin diffusion length and the apparent Py spin polarization increase with Cu thickness. A proper quantitative analysis shows that the Cu spin diffusion length is dominated by surface spin-flip scattering and that the Py and Cu thickness dependence of spin polarization is due to strong spin-flip back-scattering at the Py/Cu interface. This solves a long-standing puzzle regarding the discrepancy in Py spin polarizations obtained from different measurements. Interestingly, the Cu surface oxidation causes enhanced spin diffusion, contrary to expectations. These surface effects substantially affect the performance of lateral spin valves.

Spin valve effect across the metal-insulator transition in V2O3

We performed measurements of Py/Cu and Py/Ag lateral spin valves as a function of injection current direction and magnitude. Above a “critical” current, there is an unexpected dependence of spin injection on current direction. Positive currents show higher polarization of spin injection than negative. This implies that in addition to current-induced spin injection, there is a thermally induced injection from a spin-dependent Seebeck effect. A temperature gradient in the Py electrode, caused by Joule heating, is responsible for injecting excess spins into the non-magnetic channel. This effect has important consequences for understanding high-current spin-based devices, such as spin transfer torque devices.

Mirror symmetry in magnetization reversal and coexistence of positive and negative exchange bias in Ni/FeF2

The transition from positive to negative exchange bias can be systematically tuned with antidot arrays artificially introduced into Ni/FeF2 ferromagnetic/antiferromagnetic heterostructures. These results are a consequence of the energy balance and suggest that the nanostructure plays a key role in the formation of pinned uncompensated spin regions in the antiferromagnetic FeF2 layer. These noninterfacial magnetic moments created at the antidot faces favor the onset of positive exchange bias at lower cooling fields.

Erratum: Vortex ratchet reversal: role of interstitial vortices [Phys. Rev. B 83, 174507 (2011)]

We present a study of exchange bias in different configurations of V

Coupling of magnetism and structural phase transitions by interfacial strain

{}_{2}