# Crystal growth and magnetic structure of MnBi2Te4

## TL;DR

This study reports the synthesis, magnetic structure, and transport properties of MnBi₂Te₄ crystals, revealing antiferromagnetic order below 24K and minimal impact of magnetic order on electronic band structure, relevant for topological applications.

## Contribution

First detailed magnetic and transport characterization of MnBi₂Te₄ crystals, elucidating their magnetic structure and electronic properties for potential topological states.

## Key findings

- MnBi₂Te₄ exhibits antiferromagnetic order below 24K.
- Magnetic moments align ferromagnetically in-plane and antiferromagnetically along c-axis.
- Electronic band structure remains unaffected by magnetic order.

## Abstract

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 \textit{ab} plane but antiferromagnetically along the crystallographic \textit{c} axis. The ordered moment is 4.04(13) $\mu_{B}$/Mn at 10\,K and aligned along the crystallographic \textit{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.