The normal-state anomalous behaviours studied by internal friction of partially Sr-substituted Y123 in the underdoped range

Abstract

The internal friction of partially Sr-substituted Y(Ba1−xSrx)2Cu3O7−δ (x = 0.1, 0.2, and 0.5) ceramics with different oxygen content was measured using the vibrating-reed method from liquid nitrogen temperature to room temperature at kilohertz frequencies. A broad mechanical-energy dissipation peak and a sharp one were observed around 220 K. The position of the broad internal-friction peak does not show a systematic change with the oxygen content, and its intensity decreases after depleting a great amount of oxygen. For the sample with high oxygen concentration, another broad peak of lower intensity appeared around 150 K, which might relate to a microstructure change. At the same time, we have not found any anomalous behaviour of internal friction between 90 and 200 K for the sample with lower oxygen content, where the opening of a pseudogap for underdoped YBa2Cu3O7−δ has been observed in many other experiments. Our results provide more information about the normal-state properties of high-temperature superconductors.

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

“…Cannelli et al [4] suggested an explanation of P2: the jumping off of the oxygen atoms in offcentre sites in the CuO x chain layers. Later, in the study of the effect of Zn substitution on the two low-temperature relaxation peaks, it was proposed that P1 could be due to the hopping of apical oxygen atoms in their off-centre sites [12]. The above explanation of oxygen-atom hopping is consistent with the results of low-temperature internal friction of Sr-substituted Y123 [11].…”

“…This could be due to the disorder of the oxygen atoms in the chain layers. The appearance of a new internal friction contribution is also observed in Sr-substituted Y123 in the underdoped Y123 [12] and in YSr 2 Cu 3−x Fe x O 7−δ [18]. This could also be oxygen disorder resulting in the new internal friction contribution.…”

“…Then it is interesting to study the dependence of the P3 peak on hole density, which is important for a clear understanding of P3 and a deeper insight into the normal state of HTSCs. We have studied the lowtemperature internal friction of Sr-substituted Y123 in the underdoped range [12]. Near the optimal doping range, P3 was less sensitive to the decrease of hole density.…”

A low-temperature internal friction study of Y124 superconductors

“…It does not relate to a thermally activated process [2]. Furthermore the P3 peak does not originate from the effect of some internal surface such as grain or twin boundaries [9]. Therefore it is expected that P3 indicates a phase transition or crossover in Y123 around 220 K. Many groups suggest that the P3 peak relates to an oxygen order-disorder transition or an oxygen-glass transition.…”