Łukasz Karwacki

Influence of intermixing at the Ta/CoFeB interface on spin Hall angle in Ta/CoFeB/MgO heterostructures

When a current is passed through a non-magnetic metal with strong spin-orbit coupling, an orthogonal spin current is generated. This spin current can be used to switch the magnetization of an adjacent ferromagnetic layer or drive its magnetization into continuous precession. The interface, which is not necessarily sharp, and the crystallographic structure of the nonmagnetic metal can both affect the strength of current-induced spin-orbit torques. Here, we investigate the effects of interface intermixing and film microstructure on spin-orbit torques in perpendicularly magnetized Ta/Co40Fe40B20/MgO trilayers with different Ta layer thickness (5 nm, 10 nm, 15 nm), greater than the spin diffusion length. Effective spin-orbit torques are determined from harmonic Hall voltage measurements performed at temperatures ranging from 20 K to 300 K. We account for the temperature dependence of damping-like and field-like torques by including an additional contribution from the Ta/CoFeB interface in the spin diffusion model. Using this approach, the temperature variations of the spin Hall angle in the Ta underlayer and at the Ta/CoFeB interface are determined separately. Our results indicate an almost temperature-independent spin Hall angle of

Spin-dependent thermoelectric effects in a strongly correlated double quantum dot

{{\boldsymbol{\theta }}}_{{\boldsymbol{SH}}}^{{\boldsymbol{N}}}\approx -{\bf{0.2}}

Magnon cotunneling through a quantum dot

θSHN≈−0.2 in Ta and a strongly temperature-dependent

Determination of spin Hall angle in heavy metal/CoFeB-based heterostructures with interfacial spin-orbit fields

{{\boldsymbol{\theta }}}_{{\boldsymbol{SH}}}^{{\boldsymbol{N}}}

Thermoelectric properties of a quantum dot coupled to magnetic leads by Rashba spin-orbit interaction

θSHN for the intermixed Ta/CoFeB interface.

Spin Thermoelectric Effects in a Strongly Correlated Double Quantum Dot System

Thermoelectric transport phenomena in a single-level quantum dot coupled to ferromagnetic leads are considered theoretically in the Kondo regime. The dot is described by the Anderson model with Rashba type spin-orbit interactions. The finite-U mean field slave boson technique is used to describe transport characteristics, such as the heat conductance, thermopower and thermoelectric efficiency (figure of merit). The role of quantum interference effects in the thermoelectric parameters is also analyzed.