Engineering MnBi₂Te₄ thin films by chemical dopants and tailoring structure

As the first realized instrisic magnetic topological insulators, MnBi₂Te₄ (MBT) has been extensivly studied and shows rich novel trasnport properties and magnetic properties. As MBT is layered material with antifferomagnetic coupling between adjacent layers, it is a challenge to realize the quantum anomalous Hall effect in MBT. With molecular beam epitaxy technique,we prepared MBT thin films and tried to modify the magnetic coupling by constructing multilayer structures and co-doping method. In this work we systematically studied the magneto-electrical transport properties with the bottom gate tuning method. In the multilayer films stacked with other magnetically doped topological insulators, we observed a diversity behaviors of magnetresistance and Hall effect in different samples, which are likely due to the varible magnetic orders. Besides, we also discovered an evident evolution in Sb-doped MBT films with varying the ratio of Bi/Sb. Our study indicates that the magnetic order can be tuned in MBT based films and it paves a promissing way to control different exotic topological states.