Gate-tunable nonreciprocal thermoelectric effects on the surface states of topological insulators

Thermoelectric devices at the nanoscale offer promising routes for on-chip refrigeration and waste-heat recovery, yet most semiconductor-based implementations suffer from limited tunability and narrow operational ranges. We introduce a highly flexible thermoelectric platform based on a ballistic junction formed by two gate-tunable regions of a topological insulator surface state bridged by a magnetic barrier. We theoretically demonstrate that such device exhibits strong electrical control over both refrigeration and thermoelectric power generation via side gates. We exploit the interplay between strong spin-orbit coupling and magnetism to achieve pronounced nonreciprocal transport, asymmetric cooling and tunable diode-like behavior. To demonstrate experimental feasibility, we further analyze refrigeration efficiency and phonon-limited performance in realistic material settings.