Researchers at the University of California at Riverside used a synthetic nanoscale antiferromagnetic to control the interaction between magnons – research that could lead to faster, more energy-efficient computers.
In ferromagnetics, the electron spins point in the same direction. To make future computing technologies faster and more energy efficient, spintronics research uses spin dynamics – fluctuations in electron spins – to process information. Magnons, the quantum mechanical units of spin fluctuations, interact with each other, leading to non-linear characteristics of spin dynamics. These nonlinearities play a central role in magnetic memory, spin torque oscillators and many other spintronic applications.
For example, in the emerging field of magnetic neuromorphic networks – a technology that mimics the brain – nonlinearities are essential for tuning the response of magnetic neurons. In addition, in another frontier field of research, nonlinear spin dynamics can become instrumental.
“We predict that the concepts of quantum information and spintronics will consolidate in hybrid quantum systems,” said Igor Barsukov, assistant professor in the Department of Physics and Astronomy who led the study that appears in Applied Materials & Interfaces . “We will have to control nonlinear spin dynamics at the quantum level to achieve their functionality.”
Barsukov explained that in nanomagnets, which serve as the building blocks of many spintronic technologies, magnons exhibit quantized energy levels. The interaction between magnons follows certain rules of symmetry. The research team learned to design the interaction of magnons and identified two approaches to achieve non-linearity: breaking the symmetry of the spin configuration of the nanomagnet; and modify the symmetry of the magnons. They chose the second approach.
“Changing the symmetry of magnons is the most difficult, but also the most application-friendly approach,” said Arezoo Etesamirad, lead author of the research paper and graduate student from Barsukov’s lab.
In their approach, the researchers subjected a nanomagnet to a magnetic field that showed non-uniformity at characteristic nanometer length scales. This nanoscale non-uniform magnetic field itself must have originated from another nanoscale object.
For a source of such a magnetic field, the researchers used a nanoscale synthetic antiferromagnetic, or SAF, made up of two ferromagnetic layers with an antiparallel spin orientation. In its normal state, the SAF generates virtually no stray fields – the magnetic field surrounding the SAF, which is very small. Once it undergoes the so-called spin-flop transition, the spins become tilted and the SAF generates a stray field with nanoscale non-uniformity, if necessary. The researchers switched the SAF between the normal state and the spin-flop state in a controlled manner to turn the symmetry breaking field on and off.
“We were able to manipulate the interaction coefficient of the magnons by at least an order of magnitude,” Etesamirad said. “This is a very promising result, which could be used to design coherent magnon coupling in quantum information systems, create distinct dissipative states in neuromorphic magnetic networks, and control large excitation regimes in torque devices. of spin. “
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Material provided by University of California – Riverside. Original written by Iqbal Pittalwala. Note: Content can be changed for style and length.