To the Intrinsic Magnetism of the Bi108Sn0.02Sb0.9Te2S Topological Insulator

Abstract

Using Electron Spin Resonance spectroscopy together with the Superconducting Quantum Interference Device magnetometry, we found that the intrinsic magnetic moments, originating from the nonmagnetic structural defects of Bi1.08Sn0.02Sb0.9Te2S topological insulator form the superparamagnetic state. It represents an array of nanoscale single domain ferromagnets randomly distributed in the nonmagnetic media. Their net magnetic polarization in the absence of external magnetic field is completely averaged out. Single domain ferromagnetic particles at elevated temperatures behave magnetically in a manner analogous to the Langevin paramagnetism of moment bearing atoms. The main distinction is that the moment of the particle may be 102—103 times the atomic moment.