Temperature-driven spin-zero effect in TaAs2

Abstract

The electrical and thermo-electrical transport properties of the semimetal TaAs2 have been measured in a magnetic field applied along the [−2 0 1] direction. The resulting field dependences of the resistivity as well as the Hall, Seebeck, and Nernst coefficients below T ≈ 100 K can be satisfactorily described within the two-band model consisting of electron and hole pockets. At low temperature, all of the measured coefficients exhibit significant contributions from quantum oscillations. The fast Fourier-transform (FFT) of the oscillatory Nernst signal shows two fundamental frequencies, Fα = 105 T and Fβ = 221 T, and the second harmonic of the latter (F2β = 442 T). The ratio between the FFT amplitudes of Fβ and F2β changes with temperature in an unusual way, indicating the observation of a spin-zero effect caused by temperature change. This is likely related to the substantial temperature dependence of the Landé g-factor, which in turn may stem from the non-parabolic energy dispersion or temperature evolution of the spin-orbit coupling.