Intra-unit-cell electronic nematicity of the high-Tc copper-oxide pseudogap states

Abstract

In the high-transition-temperature (high-T(c)) superconductors the pseudogap phase becomes predominant when the density of doped holes is reduced. Within this phase it has been unclear which electronic symmetries (if any) are broken, what the identity of any associated order parameter might be, and which microscopic electronic degrees of freedom are active. Here we report the determination of a quantitative order parameter representing intra-unit-cell nematicity: the breaking of rotational symmetry by the electronic structure within each CuO(2) unit cell. We analyse spectroscopic-imaging scanning tunnelling microscope images of the intra-unit-cell states in underdoped Bi(2)Sr(2)CaCu(2)O(8 +) (delta) and, using two independent evaluation techniques, find evidence for electronic nematicity of the states close to the pseudogap energy. Moreover, we demonstrate directly that these phenomena arise from electronic differences at the two oxygen sites within each unit cell. If the characteristics of the pseudogap seen here and by other techniques all have the same microscopic origin, this phase involves weak magnetic states at the O sites that break 90 degrees -rotational symmetry within every CuO(2) unit cell.

NMR studies of pseudogap and electronic inhomogeneity in Bi2Sr2CaCu2OCrocker1, Dioguardi2, apRoberts-Warren3 et al. 2011Phys. Rev. B

“…10 Of particular interest is the fact that the electronic degrees of freedom in the pseudogap develop short range inhomogeneous mesoscopic structures that break the C 4 structural symmetry of the CuO 2 plane. [11][12][13] Inelastic neutron scattering (INS) studies of these materials reveal magnetic excitations that can be described by onedimensional stripe structures consistent with the STM results. 14,15 These inhomogeneous electronic structures may be a more general manifestations of electronic liquid crystalline phases of doped Mott insulators.…”

Doping Dependencies of Onset Temperatures for the Pseudogap and Superconductive Fluctuation in Bi2Sr2CaCu2O8+δ, Studied from Both In-Plane and Out-of-Plane Magnetoresistance Measurements

“…It is not yet conclusive whether it is a necessary ingredient (precursor) for high-T c superconductivity [1][2][3][4][5] or if it is a different ordered state. [6][7][8] In the former case, the pseudogap opening temperature T * coincides with the onset temperature of superconductive fluctuation, T sc f , and may merge with T c in the overdoped state. In the latter case, the T * behavior is independent from T sc f , and may cross it on its way to zero temperature at the quantum critical point near the optimal doping of p = 0.19.…”

“Checkerboard Stripe” Electronic State on Cleaved Surface of NdO0.7F0.3BiS2 Probed by Scanning Tunneling Microscopy

“…Another example is the high-temperature superconductivity in copper oxides 10 and iron-pnictides 11 . The superconductivity in these materials often coexists with or emerges in the proximity of some electronic ordered states [12][13][14][15][16][17][18] , which break the C 4 -symmetry of the underlying crystal lattice. Explorations of the relation between SC and the electronic ordered states have offered interesting information for understanding of the mechanisms of unconventional superconductivity.…”

“…Additionally, this technique has made a significant contribution not only to visualize the CDW 3,6 and other electronic ordered states 13,14,16,17 but also to disentangle the relationship between the superconductivity and the electronic ordered states.…”