Dynamics of Twin Boundaries and High Tc Superconductors

The formation of coherent arrays of twins in a tetragonal to orthorhombic transition and its effects on electronic properties are studied. The twin boundary oscillations (“dyadons”) have an anisotropic dispersion with frequencies typically ≲1010 sec-1 for wavevectors perpendicular to the boundaries. This results in a ~T2 contribution to the specific heat for T≳ 1°K and a linear temperature dependence of the resistivity. The unusual anisotropy yields vertex corrections which diverge at high temperatures and can enhance Tc.