Electron doping: A generic approach for realizing interlayer ferromagnetic coupling in the antiferromagnetic MnBi2Te4 family of materials

Experimentally realization of interlayer ferromagnetic (FM) coupling in antiferromagnetic (AFM) MnBi2Te4 family of materials (MBTs) plays an important role for exploring many exotic quantum phenomena, such as (quantum) anomalous Hall effect and magnetic Weyl semimetal phase. Here, we propose electron doping to realize interlayer FM coupling in layered MBTs. The mechanism is based on that electron doping can drive the Bi p orbitals of MBTs down towards the Fermi level, where the unfully Bi p orbitals indirectly allows the Mn atoms between two adjacent MBT to open a channel of the same spin, which further leads to the interlayer FM coupling. Through first-principles calculations, we demonstrate that electron doping, including Li, Na, K, Ca, Al, and Ga dopants, can indeed induce interlayer AFM to FM phase transition in MBT bilayer, accompanied by semiconducting to metallic phase transition. Specifically, the K-doped MBT hosts the Curie temperature of 53 K, which is much higher than that of pristine MBT. Further topological identification shows that topological states below the Fermi levels are well preserved when atoms are doped on the surface of MBT, which can be observed by using angle-resolved photoemission spectroscopy. Our work highlights the approach toward realizing interlayer FM coupling and paves the way for further study of quantum phenomena in MBTs as well as their magnetic applications. It is worth noting that K atoms have been successfully doped in MBT. locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon locked icon Physics Subject Headings (PhySH)First-principles calculationsMagnetic phase transitionsTopological materialsElectronic structureMagnetic systemsMonte Carlo methodsWannier function methods