Unusual Hall effect in superconducting MgB2 films -: art. no. 220506

We have investigated the temperature and magnetic field dependence of the Hall coefficient of two well-characterized superconducting MgB2 films (T-c0 = 38.0 K) in both the normal and superconducting states. Our results show that the normal-state Hall coefficient R-H is positive and increases with decreasing temperature, independent of the applied magnetic field (to 8 T). We find that R(H)(-1)proportional to T(40-300 K) and cot OH proportional toT(2)(100-300 K). As the sample is cooled below T-c(H), R-H decreases rapidly with temperature and changes sign before it reaches zero. The position and magnitude at which R-H shows a minimum depends on the applied field.