Magnetic Ordering In Superconducting Nb-doped Bi$_{2}$Se$_{3}$

Coexistence of superconductivity and magnetic order has been suggested by early studies of topological superconductor candidate, niobium doped Bi$_{2}$Se$_{3}$. In order to elucidate the interesting physics of this coexistence, we performed highly sensitive torque magnetometry to study the material’s magnetization. We observed a bump feature in the magnetization around 8 Tesla in both the superconducting and non-superconducting samples. This is distinct from the paramagnetic torque response of the parent compound, Bi$_{2}$Se$_{3}$, suggesting some interesting magnetic order in Nb-doped Bi$_{2}$Se$_{3}$.