Hall coefficient of (Cr100-xAlx)(95)Mo-5 alloy system

The temperature dependence of the Hall coefficient, RH , for the (Cr100-Al-x(x))(95)Mo-5 alloy system with 0 <= x <= 8.6, in the temperature range 2 K <= T <= 380 K and in a magnetic field of 4.5 T is reported. Anomalies in the form of an upturn were observed just below the Neel transition temperature, T-N , for the incommensurate (I) spin density wave (SDW) alloys with x <= 1.3 and commensurate (C) spin density wave (SDW) alloys with x >= 5.3. In addition to these anomalies, alloys with x = 0, 0.5, 0.9 and 8.6 show a peculiar behaviour below T-N , in which R-H increases and then decreases depicting a hump on further cooling. Remarkably R-H for the alloy with x = 0 shows a sign reversal of majority charge carriers from holes to electrons on cooling below 120 K. The crossover of majority charge carriers disappears by the addition of just 0.5 at.% Al into the base alloy with x = 0. The behaviour of the Hall coefficient for the alloys with x = 0, 0.5, 0.9 and 8.6, is explained in terms of the simple two band model in which both charge carriers contribute to magneto-transport properties. The relative magnetic contribution to the Hall coefficient, delta R-H(2K)/R-H(2K), indicate a suppression of antiferromagnetism in the concentration range 1.7 <= x <= 4.7.