Crystal growth and magnetic structure of MnBi2Te4

Millimeter-sized MnBi${}_2$Te${}_4$ single crystals are grown out of Bi-Te flux and characterized by measuring magnetic and transport properties, scanning tunneling microscope (STM) and spectroscopy (STS). The magnetic structure of MnBi${}_2$Te${}_4$ below T${}_N$ is determined by powder and single crystal neutron diffraction measurements. Below T${}_N$=24,K, Mn${}^{2+}$ moments order ferromagnetically in the $\mathit{\text{ab}}$ plane but antiferromagnetically along the crystallographic $\mathit{\text{c}}$ axis. The ordered moment is 4.04(13) ${\mu }_B$/Mn at 10,K and aligned along the crystallographic $\mathit{\text{c}}$-axis. The electrical resistivity drops upon cooling across T${}_N$ or when going across the metamagnetic transition in increasing fields below T${}_N$. A critical scattering effect was observed in the vicinity of T${}_N$ in the temperature dependence of thermal conductivity. However, A linear temperature dependence was observed for thermopower in the temperature range 2K-300K without any anomaly around T${}_N$. These indicate that the magnetic order in Mn-Te layer has negligible effect on the electronic band structure, which makes possible the realization of proposed topological properties in MnBi${}_2$Te${}_4$ after fine tuning of the electronic band structure.