Spin-Charge Interconversion at Near-Terahertz Frequencies

Published October 06, 2020

Incident terahertz radiation pumps spin current into an adjacent metal, which is converted into a charge current and charge voltage through the so-called spin Hall effect.

This work reports the first observation of the dynamical generation of a spin polarized current from an antiferromagnetic material into an adjacent non-magnetic material and its subsequent conversion into electrical signals

What did scientists discover?

This work reports the first observation of terahertz radiation that pumps spin-polarized electrical current from an antiferromagnetic material into an adjacent non-magnetic metal, followed by its subsequent conversion into ultra-fast electrical signals.

Why is this important?

The generation of spin currents in antiferromagnets occurs at terahertz frequencies, at least two orders of magnitude higher than ferromagnet-based devices, opening the way to ultrafast control of magnetic states in future spintronics applications. Although this work employed high magnetic fields, it could enable the development of tunable terahertz processors operating at very low fields, paving the way towards energy-efficient nanoscale technologies critical for applications in a wide range of areas, from data storage and communications to medical imaging.

Who did the research?

P. Vaidya¹, S. A. Morley², J. van Tol³, Y. Liu⁴, R. Cheng⁵, A. Brataas⁶, D. Lederman², E. del Barco¹

¹Univ. Central Florida; ²Univ. California-Santa Cruz; ³National MagLab; ⁴Northeastern Univ. China; ⁵Univ. California-Riverside; ⁶Norwegian Univ. of Science and Technology

Why did they need the MagLab?

The magnetic dynamics in antiferromagnetic materials are dominated by the so-called exchange interaction which causes the up/down ordering of electron spins. This relatively strong interaction results in dynamics that are much faster than those in currently employed ferromagnetic devices. Consequently, the unique spectrometers in the EMR facility at the NHMFL were essential for accessing the terahertz regime, while complete tuning of the dynamics required high magnetic fields.