Destabilization criteria of the in-plane Cu c-axis dynamics in cuprate superconductors

¹ Institute of Physics, University of Tartu - Riia 142, 51014 Tartu, Estonia
² Tallinn Technical University - Ehitajate tee 5, 19086 Tallinn, Estonia

Corresponding author: kolja@fi.tartu.ee

Received: 20 February 2001
Accepted: 13 June 2001

Abstract

Destabilization criteria of the in-plane Cu c-axis local dynamics in tetragonal La₂CuO₄ (also YBaCuO) have been found using the Green's function method. The build-up of the soft low-frequency resonances has been traced. Relatively small force constants weakenings can lead to Cu out-of-plane distortions. For the Y-system the criterion is stronger, the a-axis destabilization asks for smaller perturbations as compared with the c-axis one. The criteria found are expected to work in various realizations by doping-induced charge redistributions leading to local displacement distortion responses.