Pseudo-gap and superconducting condensate energies in the infrared spectra of Pr-doped YBa ₂ Cu ₃ O ₇

Abstract

The (a, b)-plane infrared and visible conductivity (30-30000 cm −1 ) of a 40% praseodymium-substituting yttrium YBa2Cu3O7 film displays a loss of spectral weight over two separate energy ranges when lowering the temperature. A first loss of spectral weight is present in the range 300-800 cm −1 from room temperature down to 40 K (Tc = 35 K). A further distinct spectral weight diminution appears in the superconducting phase at frequencies below 200 cm −1 . This diminution can be observed due to the high signal-to-noise ratio allowed by the large area of the thin film. We propose that the lower energy loss of spectral weight reflects the formation and the properties of the superconducting condensate.

Stabilization of three-dimensional charge order through interplanar orbital hybridization in PrxY1−xBa2Cu3O6+δ

“…We used resonant soft x-ray scattering (RSXS) at the Cu L 3 and Pr M 5 edges to investigate the CO properties in a Pr x Y 1− x Ba 2 Cu 3 O 7 sample with x ≈ 0.3 and a superconducting T c = 50 K; a concentration value chosen because it features pseudogap behavior, as measured by various probes 30 , 33 , 34 , and because it yields a T c similar to underdoped YBa 2 Cu 3 O ~6.67 , a doping level where the CO phase is maximal. Due to not having detwinned samples (Methods section), we cannot determine whether the 3D CO peak is biaxial or uniaxial.…”

“…This material was chosen because substitution by Pr, which is the largest trivalent rare-earth ion, except for Ce which does not form the YBCO structure 29 , results in the emergence of hybridization between the Pr 4 f orbitals and planar CuO 2 states 30 that yields an electronically relevant, hybridized orbital 31 with spatial extension in three dimensions, in stark contrast to the planar Cu 3 orbitals that dominate the physics of the parent compound. Unlike substitution by other rare-earth elements, such as Dy, which do not significantly alter the parent YBCO phase diagram 32 , increasing Pr substitution in the Pr x Y 1− x Ba 2 Cu 3 O 7 system continually reduces the superconducting T c , yielding a pseudogap regime 30 , 33 , 34 and eventually an antiferromagnetic insulating phase 30 , 35 – 40 . Furthermore, the in- and out-of-plane zero-temperature superconducting coherence lengths are substantially longer in Pr-YBCO than in YBCO and increase monotonically with Pr concentration 41 – 43 .…”

Terahertz Resonators Based on YBa2Cu3O7 High-Tc Superconductor

“…This also provides an effective way for modulating the superconducting state and finally the resonance frequency of a metamaterial [26]. More specifically, high-temperature superconductor cuprates (HTSCs) are the suitable candidate for facing this challenge since they provide a much broader frequency range of tunability compared to conventional Bardeen-Cooper-Schrieffer (BCS) superconductors, extending beyond 10 THz [27,28]. Furthermore THz radiation is a highly interesting spectral range for multidisciplinary research in physics, chemistry, biology, materials science, and biomedicine [29].…”

Stabilization of three-dimensional charge order through interplanar orbital hybridization in Pr$_x$Y$_{1-x}$Ba$_2$Cu$_3$O$_{6+δ}$

“…This material was chosen because of how the hybridization between the Pr 4f orbitals and the planar CuO 2 states [28] yields an electronically relevant, hybridized orbital [29] with spatial extension in three dimensions, in stark contrast to the planar Cu 3d x 2 −y 2 orbitals that dominate the physics of the parent compound. Unlike substitution by other rare-earth elements, such as Dy, which do not significantly alter the parent YBCO phase diagram [30], increasing Pr-substitution in the Pr x Y 1−x Ba 2 Cu 3 O 7 system continually reduces the superconducting T c , yielding a pseudogap regime [28,31,32] and eventually an antiferromagnetic insulating phase [28,[33][34][35][36][37][38]. Various results suggest that localized Pr 4f states are appreciably hybridized with the valence band states associated with the conducting CuO 2 planes, specifically the oxygen 2p level [39,40].…”

“…We used resonant soft x-ray scattering (RSXS) at the Cu L 3 and Pr M 5 edges to investigate the CO properties in a Pr x Y 1−x Ba 2 Cu 3 O 7 sample with x ≈0.3 and a superconducting T c =50 K; a concentration value chosen because it features pseudogap behavior, as measured by various probes [28,31,32], and because it yields a T c similar to underdoped YBa 2 Cu 3 O ∼6.67 , a doping level where the CO phase is maximal. A reciprocal space map of the KL-plane in reciprocal lattice units (rlu), measured at the Pr M 5 edge (930.3 eV) at 50 K, is shown in Figure 2A.…”