Spatially resolved electronic structure inside and outside the vortex cores of a high-temperature superconductor

Abstract

Puzzling aspects of high-transition-temperature (high-Tc) superconductors include the prevalence of magnetism in the normal state and the persistence of superconductivity in high magnetic fields. Superconductivity and magnetism generally are thought to be incompatible, based on what is known about conventional superconductors. Recent results, however, indicate that antiferromagnetism can appear in the superconducting state of a high-Tc superconductor in the presence of an applied magnetic field. Magnetic fields penetrate a superconductor in the form of quantized flux lines, each of which represents a vortex of supercurrents. Superconductivity is suppressed in the core of the vortex and it has been suggested that antiferromagnetism might develop there. Here we report the results of a high-field nuclear-magnetic-resonance (NMR) imaging experiment in which we spatially resolve the electronic structure of near-optimally doped YBa2Cu3O7-delta inside and outside vortex cores. Outside the cores, we find strong antiferromagnetic fluctuations, whereas inside we detect electronic states that are rather different from those found in conventional superconductors.

Quantum oscillations in the high- T c cuprates

“…Neutron scattering or X-ray diffraction evidence for broken translational symmetry in samples of the same composition where quantum oscillations are observed is lacking, except when doped with a non-magnetic impurity [105]. One possibility suggested is that antiferromagnetism appears only where superconductivity is suppressed in the vortex cores [107,108], becoming recognizable as a traditional antiferromagnetic phase only when superconductivity is suppressed by strong magnetic fields (causing the increased 'halos' of extended states around the vortex cores to overlap [109]) or non-magnetic impurities [61,88]. A related possibility is the growth in antiferromagnetic correlation length with field, with a low-field glassy phase evolving to a high-field broken-symmetry phase [65].…”

Antiferromagnetic spin fluctuations in the metallic phase of quasi-two-dimensional organic superconductors

“…Nuclear magnetic resonance ͑NMR͒ spectroscopy has proven to be a powerful probe of local spin dynamics in many strongly correlated electron materials. [9][10][11][12] The focus of this paper is on understanding what information about spin fluctuations can be extracted from NMR experiments on the organic chargetransfer salts.…”

Competing orders in thermally fluctuating superconductors in two dimensions

“…A number of recent perspectives [1][2][3][4][5][6][7][8] have highlighted new experimental [9][10][11][12][13][14] and theoretical [15][16][17][18][19][20][21][22][23][24][25][26][27] works exploring the interplay between the multiple order parameters which characterize the ground state of some of the cuprate superconductors. Good evidence was obtained for a strong coupling between the superconducting order and density wave order in spin/charge/bond correlations ͑described more precisely below͒.…”