Giant spin-dependent Seebeck effect from fully spin-polarized carriers in n-doped EuTiO3: a prototype material for spin-caloritronic applications

Abstract

Spin-caloritronics, the generation of spin currents and spin voltages from an applied temperature gradient, is a visionary technology with outstanding potential for novel applications and a fascinating landscape of fundamental properties. These capabilities have been revealed so far in a variety of devices typically assembled as interfaces between magnetic and non-magnetic materials. Here, using advanced ab initio calculations, we provide evidence that giant effects can be obtained in the electron-doped bulk oxide EuTiO₃. We find this material to be a half-metal, 100% spin-polarized ferromagnet for a wide range of temperatures and carrier concentrations. The combination of high electron mobility, a large Seebeck coefficient, and full spin polarization realizes the perfect conditions to achieve giant spin-polarized thermopower and huge chemical potential imbalance between the spin channels. At low temperatures, our calculations predict spin current densities ∼0.1 mA cm⁻² per unitary temperature gradient, and spin voltages of mV K⁻¹ order, which are among the highest reported so far. In addition, our analysis lays down fundamental guidelines for the design of the best suited materials for spin-caloritronic applications.