Temperature driven spin-zero effect in TaAs$_2$

TL;DR

This study investigates the temperature-dependent spin-zero effect in TaAs$_2$, revealing quantum oscillations and a significant change in the Lande g-factor likely due to non-parabolic dispersion or spin-orbit coupling variations.

Contribution

First observation of temperature-driven spin-zero effect in TaAs$_2$, linking it to changes in the g-factor and quantum oscillation behavior.

Findings

Quantum oscillations observed below 100 K.

FFT analysis shows two fundamental frequencies and a harmonic.

Unusual temperature dependence of FFT amplitude ratio indicating spin-zero effect.

Abstract

The electrical and thermo-electrical transport effects of the TaAs$_2$ semimetal were measured in a magnetic field applied along [-2 0 1] direction. The resulting field dependences of the resistivity as well as the Hall, Seebeck and Nernst coefficient below T ~ 100 K can be satisfactory described within the two-band model consisting of the electron and hole pockets. At low temperature all the measured effects exhibit significant contribution from quantum oscillations. The fast Fourier transform (FFT) of the oscillatory Nernst signal shows two fundamental frequencies, Fa = 105 T and Fb = 221 T, and the second harmonic of the latter (F2b = 442 T). The ratio between FFT amplitudes of Fb and F2b changes with temperature in an unusual way, indicating that we observe the spin-zero effect caused by temperature change. This is likely related to substantial temperature dependence of the Lande g-factor, which in turn can result from non-parabolic energy dispersion or temperature evolution of the spin-orbit coupling.