The TRR 227 kindly invites you to the joint Colloquium of the TRR 227 & FU Physics Department Colloquium.
Speaker: Prof. Dr. Arne Brataas - Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
Title: Spin insulatronics
In magnetic insulators, there are no charge currents, but spin currents can propagate over long distances. It is the propagation of disturbances in the localized magnetic moments that can carry spin currents. When magnetic insulators are in contact with metals, spin-currents can pass from the insulators to the metals via spin-transfer and spin-pumping enabled by the exchange interaction at the interfaces. These mechanisms enable electrical control over spin excitations in magnetic insulators.
We will discuss routes for electrical control of quantum coherent magnon phenomena in magnetic insulators, in ferromagnets and antiferromagnets.
First, we describe the formation of steady-state magnon condensates controlled by a spin accumulation in adjacent normal metals. Spin-transfer by this spin accumulation affects the magnetization of the ferromagnet and the staggered field of the antiferromagnet. The resulting condensation may occur even at room temperature when the spin transfer to the metal is faster than the relaxation processes in the magnet.
Second, we will discuss how antiferromagnets may exhibit long-range spin superfluidity in insulators, which studies indicate are good spin conductors. The spin superfluidity can be detected in non-local geometries and can reach several micrometers.
Third, we will discuss how magnons can mediate superconductivity in adjacent normal metals. The induced electron pairing is p-wave when the magnetic insulator is ferromagnetic and d-wave when the magnetic insulator is antiferromagnetic.
Nov 08, 2019 | 03:15 PM
Lecture Hall A - Physics Department - Freie Universität Berlin
(Arnimallee 14, 14195 Berlin-Dahlem)