Sign reversal of the Hall effect in an underdoped La1.875Sr0.125CuO4 epitaxial thin film

Abstract The magnetoresistivity ρ xx ( B ) and the Hall effect R xy ( B ) in an underdoped La 2− x Sr x CuO 4 epitaxial thin film (LSCO x =0.125) have been measured at temperatures below and above the critical temperature T c =21.5 K in magnetic fields up to 10 T. The Hall data R xy ( B ) show a linear regime at high temperatures and strong non-linear effects at low temperatures due to the superconducting fluctuations which appear at temperatures well above T c . The Hall data reveal a sign reversal below T c . In comparing the Hall effect data with the in plane voltage data V xx , we found that the minimum of the sign reversal is related to the flux flow regime of the superconducting phase but this minimum does not correspond to the maximum slope of the magnetoresistivity. The value of the magnetic field, where this minimum appears, increases with increasing temperature. The results will be compared with theories, which give an explanation of the sign reversal.