Engineering topics

Mitrofanov, Alexander

Publications and source records attributed to Mitrofanov, Alexander.

4 records

DOE OSTI2022

Effects of spin-orbit interaction and electron correlations in strontium titanate

Here, we show that the Bloch states in the conduction band of SrTiO 3 arise from the interplay between highly anisotropic hopping in subbands derived from the Ti t2g orbitals and spin-orbit coupling that mixes these orbitals. Because of the nearly flat-band characteristics for one of the principal axes, at sufficiently high doping these Bloch states become unstable with respect to electron interactions, resulting in Mott-like singlet correlations. These findings may be relevant to the anomalous electronic properties of SrTiO 3 , including its unusual superconductivity.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Effects of the dynamical magnetization state on spin transfer

We utilize simulations of electron scattering by a chain of dynamical quantum spins to analyze the interplay between the spin transfer effect and the magnetization dynamics.We show that the complex interactions between the spin-polarized electrons and the dynamical states of the local spins can be decomposed into separate processes involving electron reflection and transmission, as well as absorption and emission of magnons—the quanta of magnetization dynamics. Analysis shows that these processes are substantially constrained by the energy and momentum conservation laws, resulting in a significant dependence of spin transfer on the electron’s energy and the dynamical state of the local spins. Here, our results suggest that exquisite control of spin transfer efficiency and of the resulting dynamical magnetization states may be achievable by tailoring the spectral characteristics of the conduction electrons and of the magnetic systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2021

Nonclassical Spin Transfer Effects in an Antiferromagnet

We simulate scattering of electrons by a chain of antiferromagnetically coupled quantum Heisenberg spins, to analyze spin-transfer effects not described by the classical models of magnetism. Our simulations demonstrate efficient excitation of dynamical states that would be forbidden by the semiclassical symmetries, such as generation of multiple magnetic excitation quanta by a single electron. Furthermore, quantum interference of spin wave functions enables generation of magnetization dynamics with amplitudes exceeding the transferred magnetic moment. Here, the efficiency of excitation is almost independent of the electron spin polarization, and is governed mainly by the transfer of energy. Nonclassical spin transfer may thus enable efficient electronic control of antiferromagnets not limited by the classical constraints.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Energy and momentum conservation in spin transfer

We utilize simulations of spin-polarized electron scattering by a chain of localized quantum spins to show that energy and linear momentum conservation laws impose strong constraints on the properties of magnetic excitations induced by spin transfer. In turn, orbital and spin dynamics of conduction electrons depends on the dynamical characteristics of the local spins. Furthermore, our results suggest the possibility to achieve precise control of spin-transfer-driven magnetization dynamics by tailoring the spectral characteristics of the magnetic systems and of the driving electrons.

36 MATERIALS SCIENCE↗