Magnetotransport in the Normal State of La1.85Sr0.15Cu(1-y)Zn(y)O4 Films

摘要

We have studied the magnetotransport properties in the normal state for aseries of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with values of y, between 0 and0.12. A variable degree of compressive or tensile strain results from thelattice mismatch between the substrate and the film, and affects the transportproperties differently from the influence of the zinc impurities. Inparticular, the orbital magnetoresistance (OMR) varies with y but isstrain-independent. The relations for the resistivity and the Hall angle andthe proportionality between the OMR and tan^2 theta are followed about 70 K. Wehave been able to separate the strain and impurity effects by rewriting theabove relations, where each term is strain-independent and depends on y only.We also find that changes in the lattice constants give rise to closely thesame fractional changes in other terms of the equation.The OMR is more stronglysupressed by the addition of impurities than tan^2 theta. We conclude that therelaxation ratethat governs Hall effect is not the same as for themagnetoresistance. We also suggest a correspondence between the transportproperties and the opening of the pseudogap at a temperature which changes whenthe La-sr ratio changes, but does not change with the addition of the zincimpurities.