Critical behaviour of bulk phonons in YBa₂Cu₃O_7-δas observed by infrared absorption spectroscopy

Abstract

The frequencies and the absorption cross sections of infrared active phonons show anomalies related to the transition between the normal and superconducting phase in YBaZCu307. The excess intensity of the absorption line and the frequency shift of the mode near 585 cm-' are proportional to each other. Correlating these parameters with the thermodynamic order parameter using hard model spectroscopy leads to an order parameter of the superconducting phase which follows formally mean field theory of the BCS or Landau-Ginzburg type.

Crystal structure and paramagnetic behaviour of

“…The physical properties of tungsten trioxide, WO 3 , and its slightly oxygen-deficient analogues, WO 3−x , have attracted renewed attention because their electronic properties may shed some light on one possible pairing mechanism in high-temperature superconductors, namely Bose condensation of pre-formed bipolaron charge carriers [1][2][3][4][5][6][7][8][9][10][11][12]. Experimental suggestions of possible Bose condensation stem from the departure of the nuclear spinrelaxation rate from the Korringa law [3], the heat capacity anomaly [4,5], and the softening of phonons above the pseudo-gap in the superconducting phase [7,8,[13][14][15].…”

Kuramoto synchronization of quantum tunneling polarons for describing the dynamic structure in cuprate superconductors

“…Extending these experiments to compounds in which Co, Mn, and Ni are substituted for a fraction of the Cu went further, demonstrating that the IQTPs contribute to HTSC [28]. In addition to XAFS, there are numerous observations of anomalous phonons, some with distinct O-isotope dependence, in the E < 100 meV range in infrared(IR) [29][30][31], Raman [7]. c) The atoms circled in black in (a) form the six atom cluster used here.…”