Temperature and Magnetic Field Dependence of the Hall Coefficient on the Antiferromagnetic Chromium

抄録

The Hall coefficient, R_H, of single crystal and single Q state of pure Cr was measured as a function of temperature between 360 and 4.2 K in fields up to 42 kG. From T_N(=311 K) to 150 K, R_H showed a hump similar to the electrical resistivity and it was explained by four band model in terms of carrier reduction by the nesting of Fermi surface of the electron and the hole octahedron due to the antiferromagnetic state. In the temperature between 50 and 30 K, minima of R_H were observed and it was considered arising from freezing out of Umklapp process in electron-phonon scattering. Below 30 K, a rapid increase of R_H with decreasing temperature was observed in lower field. This result was explained by an excitation across the second order energy gap arising from the effect of the nesting. The gap was estimated to be 7.6±0.8 meV.