Measurement Of Quantum Anomalous Hall Effect In MnBi_2nTe_3n+1

Topological insulators are one of the research directions that have attracted much attention in condensed matter physics in recent years.A series of novel quantum phenomena such as the quantum spin Hall effect have been realized in topological insulator.And this system has broad application prospects in future fields such as topological quantum computing.With the rapid development of the field of topological insulators,it has been thought that the combination of topological insulators and magnetism can break the time reversal symmetry of systems and achieve phenomena such as the quantum anomalous Hall effect.The quantum anomalous Hall effect can achieve a non dissipative conductive channel with a macroscopic size（millimeter level）at zero field,which can solve a series of problems such as chip function limitations caused by the heating of electronic devices,and is helpful in solving the bottleneck of Moore’s Law in traditional computers today.The first experimentally realized magnetic topological insulator was Cr doped（Bi,Sb）₂Te₃ film,which achieved the quantum anomalous Hall effect at 30 m K.However,due to defects such as inhomogeneous doping and weak coupling in materials,the temperature at which quantum anomalous Hall effects can be observed is usually below100 m K.Therefore,people need an intrinsic magnetic topological insulator to avoid the shortcomings caused by magnetic doping.In this work,we obtained nanofilms of materials by exfoliating bulk samples of Mn Bi₄Te₇ and Mn Bi₈Te₁₃,and prepared them into devices that can characterize their electrical transport properties at low temperatures through microfabrication.When the Fermi level of Mn Bi₄Te₇ is tuned into the gap by adjusting the gate voltage,the quantum anomalous Hall effect can be observed at high fields,and the existence of non dissipative chiral edge states can be determined through nonlocal measurements.The quantum phase transition behavior from Anderson insulator at low fields to quantum anomalous Hall insulator at high fields is analyzed.This article thinks that we observe topological Anderson QAHE caused by non magnetic disorder in single SL Mn Bi₄Te₇,which is a new mechanism to realize QAHE.Some simple transport results of Mn Bi₈Te₁₃ are given,which confirm that it is not suitable as a platform for studying the quantum anomalous Hall effect compared to the Mn Bi₄Te₇ system.This will promote the further realization of the quantum anomalous Hall effect at high temperature and low field in the Mn Bi_2nTe_3n+1 system.