Continuously tunable temperature coefficient of resistivity in antiperovskite AgN_(1-x)C_xMn_3 (0 ≤ x ≤ 0.15)

摘要

The antiperovskite intermetallic compounds AgN_(1-x)C_xMn_3 (0≤x≤0.15) have been synthesized. As x increases, the temperature coefficient of resistivity (TCR) above room temperature decreases monotonically and finally changes the sign from positive to negative above x = 0.1. Meanwhile, the temperature range is gradually broadened. For x = 0.07, TCR is ～3.1ppm/K between 280 K and 375 K. Both the resistivity and its slope are insensitive to the external magnetic field, indicating an insignificant contribution from magnetic scattering or short-range magnetic ordering to the observed low-TCR. As manifested by the Hall effect, the charge carrier density in the paramagnetic state for x = 0.15 is reduced by an order of magnitude in comparison with that for x = 0. The reduction of carrier density and the enhancive disorders when x increases was proposed to be responsible for the decrease in TCR and its sign switch.