Normal-state anomalous behaviours studied by the internal friction of YBa₂Cu₃O₇  

Abstract

The internal friction of Ca partially substituted Y1−xCaxBa2Cu3O7−δ ceramics was measured using the vibrating reed method from liquid-nitrogen temperature to room temperature at kilohertz frequency. There are two thermally activated relaxation peaks (called P1 and P2 at 95 K and 120 K, respectively). The intensity of P1 almost remains unchanged with Ca substitution, while that of P2 decreases. Another internal friction peak appears around 220 K (called P3). With the increase of Ca content, the intensity of P3 decreases and the peak position shifts toward low temperature. We also have observed that Zn substitution affects P3 much less and Fe substitution seems to result in another contribution to the internal friction around 250 K. We expect that the P3 peak originates from a charge-carrier crossover and possibly has some relationship with the occurrence of the dynamic stripe at low temperature.

A low temperature internal friction study of Y0.85Ca0.15Ba2Cu3O7−δ with different oxygen content

“…In Fig. 2, P3 peak is shown to be suppressed in as-prepared sample, which is same to the results in our recent report [9]. Fig.…”

“…This result is quantities consistent with the conclusion that P3 peak is dependence on carrier density. The P3 peak which is observed in underdoped and optimal doped range, is gradually suppressed when system becomes more overdoped [9]. It should be noted that sample annealed at 1023 K where P3 peak was observed is in the underdoped range.…”

“…Then our results also supported above explanation of internal friction peaks. Our recent study shows that P2 peak was a little depressed upon Ca substitution [9]. This might be the slight decrease of the oxygen content concomitance with Ca substitution [10,12].…”

“…We observed a gradually depression of P3 peak when Y123 becomes more overdoped with the Ca substitution [9]. In this work, we study the dependence of P3 peak on the carrier density in another series of sample, Y 0:85 Ca 0:15 Ba 2 Cu 3 O 72d with different oxygen concentrations, which was quenched from high temperature.…”

A low-temperature internal friction study of Y124 superconductors

“…In our recent study we related the P3 peak in Y123 to a crossover of carrier dynamics [5]. Another possible explanation for the P3 peak is the stripe explanation [15], which was proposed in a helium-ion channelling experiment study of Y123 [13]. The strong coupling between carriers and the local lattice plays an important role in the sensitivity of internal friction to carrier transformation.…”