Compared to their electronic counterparts in topological band theory, much less in known about the topology of spin wave excitations in a general magnetic order. Here we provide a generic theory framework to classify and compute the topology of magnons, by mapping an arbitrary linear spin wave into a local free-fermion Hamiltonian with exactly the same spectrum, symmetry implementation and band topology. This allows us to achieve a full classification and calculation on any topological properties of magnon bands. We apply this fermionization approach to honeycomb Kitaev magnet α-RuCl3, and show the existence of topologically protected magnon band crossings, and field-induced magnon Chern bands under small magnetic fields.

Associate Professor, 2019-Now

Dr. Yuan-Ming Lu, Assistant Professor, OSU, 2015-2019

Ph.D., Physics, Boston College, 2011

B.S., Tsinghua University, 2007

The research in Professor Yuan-Ming Lu’s group focuses on (1) topological phases in condensed matter physics and (2) physics of strongly correlated systems. We are interested in novel quantum phases of matter emergent from the strong electronic interactions in materials, which cannot be described by local order parameters. Using a combination of numerical and analytical approaches we will study the exotic physical properties of these topological phases, such as fractional charge/statistics, robust edge/surface states, and quantized response. We are also interested in the material realizations and experimental signatures of these topological phases, as well as associated novel quantum critical phenomena.