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تسجيل مستخدم جديدSystematic evolution of the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6} in a wide doping range
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Recently we have succeeded in growing a series of high-quality Bi_{2}Sr_{2-x}La_{x}CuO_{6} crystals in a wide range of carrier concentrations. The data of rho_{ab}(T) and R_H(T) of those crystals show behaviors that are considered to be canonical to the cuprates. The optimum zero-resistance T_c has been raised to as high as 38 K, which is almost equal to the optimum T_c of La_{2-x}Sr_{x}CuO_{4}.
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We report that it is possible to obtain a series of high-quality crystals of La-doped Bi-2201, of which the transport properties have been believed to be dirtier than those of other cuprates. In our crystals, the normal-state transport properties dis
play behaviors which are in good accord with other cuprates; for example, in the underdoped region the in-plane resistivity rho_{ab} shows the pseudogap feature and in the overdoped region the T dependence of rho_{ab} changes to T^n with n > 1. The characteristic temperatures of the pseudogap deduced from the resistivity and the Hall coefficient data are presented.
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ividly debated. One popular class of models posits electronic phase separation, where the superconducting phase fraction decreases with doping, while some competing phase (e.g. ferromagnetic) progressively takes over. A problem with this scenario is that all the way up to the dome edge the superconducting transition remains sharp, according to mutual inductance measurements. However, the physically relevant scale is the Pearl penetration depth, $Lambda_{P}$, and this technique probes the sample on a length scale $L$ that is much larger than $Lambda_{P}$. In the present paper, we use local scanning SQUID measurements that probe the susceptibility of the sample on the scale $L << Lambda_{P}$. Our SQUID maps show uniform landscapes of susceptibility and excellent overall agreement of the local penetration depth data with the bulk measurements. These results contribute an important piece to the puzzle of how high-temperature superconductivity vanishes on the overdoped side of the cuprates phase diagram.
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limits on any possible time-reversal symmetry breaking fields that could be associated with the pseudo-gap. Comparison between experimental limits and proposed circulating current states effectively eliminates the possibility that such states exist in this family of materials.
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omagnetic (AF) phase. The second magnetic resonace, analyzed in terms of in-plane spin anisotropy, shows unconventional behavior within the AF state and led to the discovery of collective spin excitations pertaining to a field induced magnetically ordered state. This state persists in a 9 T field to more than 100 K above the N{e}el temperature in x = 0.01.
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