Higher order van Hove singularities in two-dimensional bands

Speaker: Dr Anirudh Chandrasekaran (Boston & 含羞草视频)

Title: Higher order van Hove singularities in two-dimensional bands

Abstract: In this talk, I will summarize the results of a recent work of ours, exploring higher order van-Hove singularities in two dimensional solids. These are exotic band singularities that occur when some parameters in the system are tuned, such as pressure, bias voltage, twist angle, etc. They have distinct signatures manifesting as power law divergence in the density of states and some other physical quantities such as such as various susceptibilities. In our work, we import the framework of catastrophe theory to classify and describe the seventeen singularities that are mathematically guaranteed to be the typical ones to occur in two dimensional bands. We further explore the connection with symmetry and further classify the singularities with respect to the wallpaper groups in two dimensions.