Coincident onset of charge-density-wave order at a quantum critical point in underdoped YBa2Cu3Ox

Abstract

The recently demonstrated x-ray scattering approach using a free electron laser with a high field pulsed magnet has opened new opportunities to explore the charge density wave (CDW) order in cuprate high temperature superconductors. Using this approach, we substantially degrade the superconductivity with magnetic fields up to 33 T to investigate the onset of CDW order in YBa 2 Cu 3 O x at low temperatures near a putative quantum critical point (QCP) at p 1 ∼ 0.08 holes per Cu. We find no CDW can be detected in a sample with a doping concentration less than p 1 . Our results indicate that the onset of the CDW ground state lies inside the zero-field superconducting dome, and broken translational symmetry is associated with the putative QCP at p 1 .

Locally commensurate charge-density wave with three-unit-cell periodicity in YBCO

“…Let us first summarize our main result at the qualitative level: the 3D long-range CDW in YBCO is unidirectional (consistent with previous studies [26,[30][31][32][33]) and, at the local scale probed by NMR, commensurate with the lattice. The incommensurability found in X-ray scattering studies must thus be explained by the presence of an array of discommensurations.…”

“…2. This is no surprise, as the unidirectional character of the high-field CDW was already established from the observation of similarlysplit 63 Cu line shapes [26] as well as from X-ray scattering [29][30][31][32][33]. Experimentally, the total charge modulation is not purely unidirectional in high fields since the long-range unidirectional CDW coexists with the shortrange bi-directional CDW [15,29].…”

“…Among cuprates showing incommensurate short-range CDW order and no spin-order, YBa 2 Cu 3 O y (YBCO) is distinguished by 1) larger values of the CDW correlation length in zero-field and 2) the presence of threedimensional (3D) long-range CDW order, observed by quenching superconductivity in high magnetic fields [4,[26][27][28][29][30][31][32][33] or applying strain to the sample [16,34,35]. According to X-ray scattering studies, the 3D CDW is uni- C o m m e n s u r a t e q = 1 / 3 , φ = π ν-ν 0 ( u n i t s o f ∆ν)…”

Dynamical charge density fluctuations pervading the phase diagram of a Cu-based high- T c superconductor

“…Therefore, were it not for the competing superconducting order that quenches the critical behavior of CDW, 3D CDW would occur for p < pc and T < T3D without any application of magnetic field. The static 3D CDW dome is centered at p1/8 and is delimited by two QCPs at p  0.08 and 0.17 (29,30); inside that doping range, above T3D and below TQC, quasi-critical CDW, precursors of the static 3D CDW, are present. character and, due to strong quantum-thermal dynamical fluctuations, they acquire a truly static character only below T3D, which is, for (Y,Nd)BCO, smaller than Tc, thus requiring strong magnetic fields or epitaxially-grown samples to suppress superconductivity to obtain static 3D CDW.…”

Crossover from charge density wave stabilized antiferromagnetism to superconductivity in Nd1−xLaxNiC2 compounds

“…In contrast, in PrNiC 2 the magnetic anomaly has been found to have a constructive impact on the nesting properties 2,21 . In such a group of materials, an even more fertile field allowing the exploration of these interactions opens up when two competing magnetic or electronic ground states tend towards zero temperature and the quantum fluctuations corresponding to them collide at a quantum critical point (QCP) [33][34][35][36][37][38] . A quantum critical point could be revealed and thus explored by tuning the ground state via nonthermal parameters such as pressure, composition or magnetic field.…”