# Singular paramagnetism of topological insulator surfaces

Magnetic susceptibility of several common topological insulators (Bi2Se3,Sb2Te3, Bi2Te3) is singular at low field, $\chi(B=0)-\chi(B)\sim |B|+…$, as reported by Zhao et.al (Nature Materials — in press).  I will summarize experimental facts, including unambiguous identification of surface origins of this singularity, as well as some theoretical considerations.