Overview
Welcome to my homepage!
My primary research interest lies in condensed matter physics with a focus on spintronics, magnetism, and magnetic materials. I study both fundamental physics and innovative applications arising from the interplay between spin, charge, mechanical, and thermal transport in a wide variety of magnetic materials, especially antiferromagnetic thin films and nanostructures. In particular, I exploit the geometric and topological concepts to explore novel features associated with electronic band structures and spin textures. Inspirations in my research originate from experimental discoveries as well as mathematical intuitions. I am actively collaborating with experimentalists.
Ambitious young students with passions in scientific research are encouraged to join my group. My email: rancheng@ucr.edu
Research
In the last decade, one of the most exciting developments in my field is the recognition of antiferromagnets (AFM) as active spintronic materials. An appealing feature of AFM is that they can be manipulated in the Terahertz regime: two orders of magnitude faster compared to the widely-used ferromagnetic materials. I have been a leading player in this emerging frontier since my graduate study at UT-Austin, where my prediction of spin pumping and spin-transfer torques in AFM was recognized by the community as one of the foundational works in this field.
Besides ultrafast spin dynamics and its potential applications, I am especially interested in a more fundamental aspect of AFM. As schematically shown in the Figure, spin-wave excitations (or magnons) are doubly degenerate. The two circularly-polarized modes are analogous to electromagnetic waves with corresponding polarization; they carry opposite spins and form an internal degree of freedom capable of encoding information. This crucial fact (which is only true in AFM) allows us to explore the magnonic counterparts of phenomena usually associated with either the photon spin or the electron spin, opening an intriguing playground for both fundamental physics and innovative device concepts.
