Title: New physics in symmetry-breaking antiferromagnets
Abstract: Central to the study of spin-related phenomena is the capability to create spin polarized states. The conventional way of creating spin polarization entails the involvement of net magnetization or spin-orbit coupling (SOC). The latter entails heavy elements that lead to weak bonds and undesirable defects. The recent discovery of unconventional momentum-dependent non-relativistic spin splitting (NRSS) in certain symmetry-breaking antiferromagnets provides an alternative method for achieving the goal that holds promise for antiferromagnetic spintronics. This phenomenon, envisioned by Pekar and Rashba in 1964, arises from the intrinsic microscopic magnetic fields of these materials. Despite having zero net magnetization, NRSS AFMs exhibit split energy bands with opposite spin polarization—a characteristic feature of ferromagnets (FMs). This resemblance to FMs endows them with a multitude of exotic physical properties. Due to these unique characteristics, a new term, “altermagnet” has recently been coined to describe this special class of antiferromagnets. In this colloquium, I will be highlighting my journey in the process of the discovery of new physics and materials, the people I have been interacting with, and the lessons I have learned along the way.