Thermoelectric power in off-stoichiometric ThAsSe system

Transport properties of ThAsSe single crystals with various As-Se chemical composition were investigated in the temperature range 4.2-300 K. Electrical resistivity significantly decreases with increasing off-stoichiometry (As/Se content ratio around 2), although the negative temperature coefficient of the resistivity is observed down to liquid-helium temperature. On the other hand, an overall temperature dependence of the thermoelectric power is much less affected by a distinct deviation from the stoichiometry. This points out that a change of the electron density dominates effects incorporated by structural disorder