Ferroelasticity in Y-Ba-Cu-O. II. Relaxational effects

Abstract

The “spring-defect model” developed by us earlier to discuss ferroelasticity, exhibited in the orthorhombic phase of YBa₂Cu₃O_7–δ (Y-Ba–Cu–O), is used to analyze anelastic relaxation around the paraelastic to ferroelastic phase transition under the influence of an external inhomogeneous stress. The kinetics of the underlying Hamiltonian representing strain-strain interactions is treated within mean-field theory. The relaxation-response relation of linear response theory is employed to derive explicit expressions for the anelastic strain, the frequency-dependent compliance and the internal friction in terms of the basic parameters of the spring-defect model.

Key Words:

• Y-Ba-Cu-O
• ferroelasticity
• anelastic relaxation
• order-disorder transition
• internal friction