Physics & Astronomy Colloquium – Fall 2019 – Cheng

Speaker: Ran Cheng (University of California, Riverside)

Title: Antiferromagnetic Spintronics – A New Twist in Ultrafast Materials

Abstract: In the past decade, antiferromagnetic materials rapidly emerged as a new frontier in materials science because they can be operated at the Terahertz frequency range, opening a new pathway towards ultrafast materials. However, a pivotal but less known physical characteristic of antiferromagnets is that the spin-wave excitations (or magnons) allow for an intrinsic degree of freedom – chirality – to encode information. This unique feature enables a plethora of intriguing physical phenomena and novel device concepts that are impossible in traditional ferromagnetic systems. In a generic manner, I will introduce recent discoveries and research highlights in antiferromagnetic spintronics including electrical generation of coherent Terahertz signals, thermal control of spin current, magnon-induced interactions, and so on. Particularly, I will reveal that the non-trivial physical behavior of antiferromagnets is related to magnons, which are charge neutral quasi-particles that can transport spin angular momenta over long distances without incurring Joule heating. Antiferromagnetic spintronics not only enables a vibrant playground for new fundamental physics, but also initiates a new twist in ultrafast magnetic materials.