Searcharxiv⌕ Search

arXiv subjects

I. Weymann

Publications and source records attributed to I. Weymann.

38 records · Page 3Linked to original sources
arXiv2005

Cotunneling through a quantum dot coupled to ferromagnetic leads with noncollinear magnetizations

Spin-dependent electronic transport through a quantum dot has been analyzed theoretically in the cotunneling regime by means of the second-order perturbation theory. The system is described by the impurity Anderson Hamiltonian with arbitrary Coulomb correlation parameter $U$. It is assumed that the dot level is intrinsically spin-split due to an effective molecular field exerted by a magnetic substrate. The dot is coupled to two ferromagnetic leads whose magnetic moments are noncollinear. The angular dependence of electric current, tunnel magnetoresistance, and differential conductance are presented and discussed. The evolution of a cotunneling gap with the angle between magnetic moments and with the splitting of the dot level is also demonstrated.

cond-mat.mes-hall↗
arXiv2005

Macroscopic description of current induced switching due to spin-transfer

We develop a macroscopic description of the current-induced torque due to spin transfer in a layered system consisting of two ferromagnetic layers separated by a nonmagnetic layer. The description is based on i) the classical spin diffusion equations for the distribution functions used in the theory of CPP-GMR, ii) the relevant boundary conditions for the longitudinal and transverse components of the spin current in the situation of quasi-interfacial absorption of the transverse components in a magnetic layer. The torque is expressed as a function of the usual parameters derived from CPP-GMR experiments and two additional parameters involved in the transverse boundary conditions. Our model is used to describe qualitatively normal and inverse switching phenomena studied in recent experiments. We also present a structure for which we predict only states of steady precession above a certain critical current. We finally discuss the limits of a small angle between magnetic moments of the ferromagnetic layers and of vanishing imaginary part of the mixing conductance.

cond-mat.mes-hall↗