prof. dr hab. Tomasz Dietl, IF PAN

Spin dynamics in magnetic nanostructures: quantum vs. semiclassical approach

A number of quantum models and corresponding numerical diagonalization procedures have been proposed to describe spin dephasing of an electron injected to a quantum dot containing typically 103 to 106 nuclear magnetic moments. These theoretical studies have revealed many unanticipated behaviors assigned to the quantum nature of the bath spins [1]. A question then arises whether it is justified to describe spin dynamics of spintronic devices (having now diameters down to 11 nm) us¬ing semiclassical approaches, in which injection of electron spins is treated quantum mechanically but spin dynamics is described by using the essentially classical Landau-Lifshitz-Gilbert equation. In our work [2] we provide a formalism suitable to describe experimental results in a wide parameter space, allowing also to benchmark various implementations of quantum theory. Our approach to this central spin problem is also suitable for examining dissipation-less dynamics of confined superconductors and ultra-cold gases. [1] A. Faribault and D. Schuricht, Phys. Rev. Lett. 110, 040405 (2013), and references therein. [2] T. Dietl, Phys. Rev. B 91, 125204 (2015).