Observation of two types of charge-density-wave orders in superconducting La2-xSrxCuO4

Abstract

The discovery of charge- and spin-density-wave (CDW/SDW) orders in superconducting cuprates has altered our perspective on the nature of high-temperature superconductivity (SC). However, it has proven difficult to fully elucidate the relationship between the density wave orders and SC. Here, using resonant soft X-ray scattering, we study the archetypal cuprate La 2- x Sr x CuO 4 (LSCO) over a broad doping range. We reveal the existence of two types of CDW orders in LSCO, namely CDW stripe order and CDW short-range order (SRO). While the CDW-SRO is suppressed by SC, it is partially transformed into the CDW stripe order with developing SDW stripe order near the superconducting T c . These findings indicate that the stripe orders and SC are inhomogeneously distributed in the superconducting CuO 2 planes of LSCO. This further suggests a new perspective on the putative pair-density-wave order that coexists with SC, SDW, and CDW orders.

Spectroscopic fingerprint of charge order melting driven by quantum fluctuations in a cuprate

“…In the superconducting state, while the quasielastic charge order signal decreases with temperature, the interplay between charge order fluctuations and bond-stretching phonons in the form of a Fano-like interference increases, an observation that is incompatible with expectations for competing orders. Invoking general principles, we argue that this behaviour reflects the properties of a dissipative system near an orderdisorder quantum critical point, where the dissipation varies with the opening of the pseudogap and superconducting gap at low temperatures, leading to the proliferation of quantum critical fluctuations, which melt charge order.Charge order (CO), which is ubiquitous in hole-doped cuprates [5][6][7][8][9][10][11][12][13][14] , is accompanied by a negligible lattice deformation (approximately 0.1 pm, ref. 15 ); however, signatures of valence electron density modulations due to CO can be detected by resonant inelastic X-ray scattering (RIXS) at the Cu L edge.…”

Strange metal behaviour from charge density fluctuations in cuprates

“…A step forward in the identification of low energy excitations that might be responsible for the strange-metal behaviour was recently taken by means of resonant X-ray scattering (RXS), performed on Nd 1+x Ba 2−x Cu 3 O 7−δ (NBCO) and YBa 2 Cu 3 O 7−δ (YBCO) thin films 12 . After the first experimental evidence, these excitations have been demonstrated to be a common feature of different families of cuprates, namely HgBa 2 CuO 4+δ 13 , La 2−x Sr x CuO 4 [14][15][16] , La 2−x Ba x CuO 4 17,18 , and La 1.675 Eu 0.2 Sr 0.125 CuO 4 19 , thereby indicating that these excitations may well provide a generic scattering mechanism in all cuprates.…”

Hints for the nematic pseudogap in the nearly optimally doped La2−xSrxCuO4 superconductor

“…Noteworthy, CDW short-range order was recently detected in an extended range of temperatures for La 2-x Sr x CuO 4 [56] and electron nematicity may arise via a thermal or quantum phase transition from the proliferation of topological defects of the stripe (i.e., smectic) state [57]. A similar behavior was also observed in NbSe 2 , where short-range CDW survived beyond the phase coherence transition [58].…”

“…The lattice obviously breaks fourfold symmetry in the low-temperature orthorhombic phase, but the crystallographic anisotropy is much smaller than the one observed in transport. Moreover, the electrical resistivity in thin films of La 2-x Sr x CuO 4 , which were forced to retain tetragonal symmetry, still exhibited twofold symmetry [56] [normalized to the value of −( S − S max )/T at T = 50 K] are superimposed on the plot as yellow stars. The inset presents exemplary temperature dependences of ν/T for YBa 2 Cu 3 O y with a hole concentration p = 0.12 (YBCO) [38], Ba(Fe 0.955 Co 0.045 ) 2 As 2 (Ba-122) [37], and FeTe [21], along with the respective Haller equation fits.…”

“…Using data from Ref. [56], we have superimposed the height of the CDW peak for similarly doped La 2-x Sr x CuO 4 (x = 0.144) on the temperature dependences of the thermoelectrical anisotropies in Fig. 4.…”