Transport properties of La2 − xSrxCuO4 epitaxial thin films in high magnetic fields

Abstract We have investigated the magnetotransport of La 2 −  x Sr x CuO 4 (0.045⩽ x ⩽0.25) epitaxial thin films in pulsed fields up to μ 0 H =50 T. Above a certain temperature T * , the temperature dependence of the resistivity ρ ( T ) is linear and between T * and the superconducting critical temperature T c , ρ ( T ) is superlinear. This observation is universal for all underdoped films. The high field data ρ ( T , H 0 ) from underdoped and slightly overdoped samples reveal a metal-to-insulator like transition (MIT) at low temperatures. We have determined the detailed dependence of the minimum in the ρ ( T ) curves as a function of the Sr-content x . The MIT can be analyzed by calculating the k F l product from the resistivity data; here k F is the Fermi wave vector and l is the mean free path. We can describe the insulating behavior at low temperatures of samples with k F l k F l >1 the divergence of the resistivity follows a power ( T − α ( α >0)) or a logarithmic (ln(1/ T )) law, depending on the Sr-content. This ρ ( T ) divergence is probably associated with the formation of the pseudogap and the pinning of the fragmented charge stripes at low temperatures.