Low-frequency internal friction near the antiferromagnetic phase transition in YBa2Cu3O7_8

The temperature spectra of low-frequency internal friction and shear modulus of YBa2Cu3O7-8 ceramics with δ = 0.3-0.8 have been measured. The investigations have shown a number of anomalous features which depend on the annealing treatments designed to change the oxygen concentration. A qualitative explanation is presented within the framework of antiferromagnetic phase transition (δ ≥ 0.6) and martensite-like transformation related to a rearrangement of oxygen atoms.

Keywords:

• Superconductor
• internal friction
• elastic modulus
• phase transition
• oxygen deficiency
• antiferromagnetic ordering