Influence of spin arrangement on thermopower in ZnxCuyCrzSe4 spinels

The thermopower analysis carried out on ZnxCuyCrzSe4 spinel single crystals show that the ferrimagnetic spin arrangement in the range 0.49 ≤ y ≤ 0.72 makes easier the carrier diffusion from one side and hinders both the spin wave propagation and the transfer of the phonon momentum to the electron gas from the other. The opposite behaviour for the ferromagnetic spin arrangement in the range 0.81 ≤ y ≤ 0.95 was observed. In particular, the maxima contributions to the total thermopower give a magnon component (9 μV/K) of ferromagnetic samples in the temperature range 25–100 K, a phonon component (20 μV/K) of ferromagnetic samples in the temperature range 150–200 K and a diffusion component (47 μV/K) of ferrimagnetic samples in the temperature range 250–400 K. The impurity component of thermopower does not significantly depend on a kind of spin coupling and it increases with increasing non-stoichiometry of a sample (x + y + z ≠ 3). Its maximum value does not exceed 2.5 μV/K at 400 K.