Anisotropic resistivity and Hall effect inMgB2single crystals

We report resistivity and the Hall-effect measurements in the normal and superconducting states of ${\mathrm{MgB}}_2$ single crystals. The resistivity has been found to be anisotropic with slightly temperature-dependent resistivity ratio of about 3.5. The Hall constant, with a magnetic field parallel to the Mg and B sheets, is negative in contrast to the holelike Hall response with a field directed along the c axis, indicating presence of both types of charge carriers and, thus, the multiband electronic structure of ${\mathrm{MgB}}_2.$ The Hall effect in the mixed state shows no sign change anomaly, reproducing Hall-effect behavior in clean limit type-II superconductors.