AlbaNova and Nordita Colloquium

Spin Insulatronics

by Arne Brataas (NTNU Trondheim)


An electron has a spin as well as a charge. Conventional electronics and spintronics are based on the motion of mobile electrons in conductors. Spintronics, the utilization of spin in electronic devices, has revolutionized data storage and enabled Apple’s iconic devices iPod, iPhone, and iPad. Spin Insulatronics is profoundly different because there are no moving charges that generate heat. In magnetic insulators, spin information can, nevertheless, propagate. 

Controlling electric signals through the deployment of magnetic insulators can facilitate a revolution in information and communication technologies. We will discuss to what extent spin in antiferromagnetic and ferromagnetic insulators couple to currents in adjacent conductors. Since spin signals in insulators have extremely low power dissipation, overcoming the limitations can enable low-power technologies such as oscillators, logic devices, non-volatile random-access memories, interconnects, and perhaps even quantum information processing.

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.