科研之友
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摘要
The fundamental physics of cuprate superconductivity is still much deliberated after three decades of research. In contrast to phononic or polaronic roots, some major theories promote a magnetic origin. In this perspective, we review cuprate magnetism, as probed by muon-spin-rotation (mu SR) in RBa2Cu3O7-delta (RBCO), Bi2Sr2CaCu2O8+x(Bi2212) and Tl2Ba2Ca2Cu3O10+x (Tl2223). Site-search RBCO studies show that muons localize and probe in locations away from the superconducting CuO2 planes. Maximum entropy (MaxEnt, ME) analysis of transverse field mu SR data of GdBa2Cu3O7-delta (GdBCO) indicates that the muon probes in an undisturbed insulating environment, allowing mu SR to detect (weak) magnetic features in these cuprates. Concerning Varma's predicted loop currents, MaxEnt has shown weak mu SR signals for GdBCO in zero field above and below the critical temperature, T-c; these are near the predicted similar to 100 Oe. Concerning Zhang's predicted antiferromagnetism (AF) connected to the vortex cores, we have observed Lorentzian relaxation of cuprate vortex signals below half T-c, consistent with AF-broadening effects. For both Bi2212 and Tl2223, Lorentzians describe the mu SR vortex signals much better below 0.
- 出版日期2015-10-20
