Exploring intertwined orders in cuprate superconductors

Abstract

The concept of intertwined orders has been introduced to describe the cooperative relationship between antiferromagnetic spin correlations and electron (or hole) pair correlations that develop in copper-oxide superconductors. This contrasts with systems in which, for example, charge-density-wave (CDW) order competes for Fermi surface area with superconductivity. La$_{2-x}$Ba$_x$CuO$_4$ with $x=0.125$ provides an example in which the ordering of spin stripes coincides with the onset of two-dimensional superconducting correlations. The apparent frustration of the interlayer Josephson coupling has motivated the concept of the pair-density-wave superconductor, a state that theoretical calculations show to be energetically competitive with the uniform $d$-wave superconductor. Even at $x=0.095$, where there is robust superconductivity below 32~K in zero field, the coexistence of strong, low-energy, incommensurate spin excitations implies a spatially modulated and intertwined pair wave function. Recent observations of CDW order in YBa$_2$Cu$_3$O$_{6+x}$ and other cuprate families have raised interesting questions regarding the general role of charge modulations and the relation to superconductivity. While there are differences in the doping dependence of the modulation wave vectors in YBa$_2$Cu$_3$O$_{6+x}$ and La$_{2-x}$Ba$_x$CuO$_4$, the maximum ordering strength is peaked at the hole concentration of 1/8 in both cases. There are also possible connections with the quantum oscillations that have been detected about the same hole concentration but at high magnetic fields. Resolving these relationships remains a research challenge.Comment: 7 pages, for the proceedings of ECRYS-201

Phase diagrams of a 2D Ising spin-pseudospin model

“…One of the topical problems in the physics of high-T c cuprates is the coexistence and competition of the spin, superconducting, and charge orderings. The studying of the interplay between magnetism and superconductivity in cuprates has a long history [1,2,3]. Over the last fifteen years, a wealth of experimental results has suggested the presence of the charge ordering [4,5,6,7,8,9,10,11,12,13,14] and the interplaying spin and charge orderings [15,16,17,18,19,20,21] in cuprates.…”

Spatially modulated susceptibility in thin film La2−xBaxCuO4

“…Due to the point spread function of the pickup loop, the observed amplitude is a lower bound. The periods of the striae range between one and four microns, approximately a thousand times larger than the periods of stripe phases such as the spin and charge density waves that have been measured in bulk samples using neutron and x-ray diffraction techniques, [19][20][21] but comparable to the Pearl lengths in our films. Strikingly, we found that magnetic vortices tend to pin on the diamagnetic maxima of the striae, rather than the minima.…”

Staging superstructures in high-TcSr/O codopedLa2−xSrxCuO4+yRay1, Andersen2, Jensen3 et al. 2017Phys. Rev. B5040View full textAdd to dashboardCite

“…The coexistence of similar electronic phases has been explained in other cuprates as being intertwined in a spatially self-organized pattern with order parameters modulated along the c axis [36,37]. These systems (La 2−x Ba x CuO 4 , La 2−x−y Nd y Sr x CuO 4 , YBa 2 Cu 3 O 6+x ), however, all seem frustrated such that either bulk 3D superconductivity [38,39] or static antiferromagnetic order [40] is suppressed.…”