Sensor-free, self-regulating thermal switching via anomalous Ettingshausen effect and spin reorientation in DyCo5

Abstract

We propose a sensor-free, self-regulating thermal switch that combines the anomalous Ettingshausen effect with a temperature-driven spin reorientation transition (SRT) in the rare-earth cobalt compound DyCo5. Using density functional theory and the Kubo linear-response formalism, we compute the anomalous Hall conductivity σxy(ε) and the finite-temperature anomalous Nernst conductivity αxy(T) for two magnetization directions, M∥c and M⊥c. While the intrinsic σxy at the Fermi level remains sizable for both orientations, αxy exhibits about two orders of magnitude contrast in the SRT temperature window. This contrast is consistent with the low temperature Mott relation through the energy slope ∂εσxy(ε)|EF and is traced to strongly peaked Berry curvature hot spots generated by spin–orbit coupling induced avoided crossings of Co 3d bands. Combining αxy with longitudinal transport coefficients, we estimate device-level metrics, namely, the anomalous Nernst thermopower SANE and the Ettingshausen coefficient ΠAEE=TSANE, and demonstrate robust orientation-controlled switching under a fixed in-plane bias current. These results establish a materials based route to compact thermal control without external sensors or feedback electronics and provide a concrete example that the proposed principle can be realized in an existing ferromagnet.