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

Abstract

We have investigated the magnetotransport of La2-xSrxCuO4 (0.045 less than or equal to x less than or equal to 0.25) epitaxial thin films in pulsed fields up to mu(0)H = 50 T. Above a certain temperature T*, the temperature dependence of the resistivity rho(T) is linear and between T* and the superconducting critical temperature T-c, rho(T) is superlinear. This observation is universal for all underdoped films. The high field data rho(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 rho(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 < 1 by a variable range hopping conductivity. For samples where k(F)l > 1 the divergence of the resistivity follows a power (T-x(alpha > 0)) or a logarithmic In(l/T)) law, depending on the Sr-content. This p(T) divergence is probably associated with the formation of the pseudogap and the pinning of the fragmented charge stripes at low temperatures. (C) 2004 Elsevier B.V. All rights reserved.