  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.
