Within the framework of Büttiker’s gauge invariant and charge conservation dc transport theory, the spin-dependent thermal and electrical transport in a ferromagnet-insulator-ferromagnet tunnel junction is investigated at finite bias voltage and finite temperature. It is observed that the relative orientations of magnetizations in the two ferromagnetic (FM) electrodes as well as temperature have remarkable effects on the differential conductance, thermopower, Peltier effect, and thermal conductivity. At low temperature the quantum resonant tunneling is predominant, leading to the deviation of classical transport theory, while the transport of electrons are crucially governed by thermal processes at high temperature. The so-called spin-valve phenomenon is clearly uncovered for both the differential conductance and the thermal conductivity at low temperature. The Wiedemann-Franz law is examined, and the inelastic tunneling spectroscopy is also discussed. Our findings are expected to be measured in the near future.

DOI:https://doi.org/10.1103/PhysRevB.63.224419