In-Plane Field Induced Half Quantized Hall Conductivity in Trilayer Magnetic Topological Insulator

The parity anomaly originates in high-energy physics as a property of (2 + 1)-dimensional gauge theory. In condensed matter, it manifests through the physics of a single Dirac cone and with the transport signature of a half-quantized Hall conductivity (hQHC). Here, a new route is reported to achieve hQHC in trilayer magnetic topological insulators with different magnetic dopants on the top and bottom surfaces under in-plane magnetic fields. Additionally, angle-resolved magneto-transport measurements provide detailed information on the different perpendicular magnetic anisotropy energies of top and bottom surface magnetism and offer insights into the manipulation of the topological magnetoelectric effect via field orientation. The interlayer exchange coupling can be further tuned by non-magnetic spacer thickness, offering a technical pathway to stabilize a single Dirac cone with hQHC for investigating the parity anomaly and designing novel topological quantum devices.