Spin dynamics in the pressure-induced two-leg ladder cuprate superconductor Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$

TL;DR

This study investigates the spin dynamics in a pressure-induced cuprate superconductor using a kinetic energy driven mechanism, revealing pressure-dependent spin correlations and relaxation behaviors consistent with experiments.

Contribution

It introduces a theoretical analysis of spin dynamics in Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$ under pressure, highlighting the evolution of spin correlations and relaxation times.

Findings

Incommensurate spin correlations in underpressure regime.

Emergence of commensurate spin fluctuations at optimal and overpressure.

Temperature linear dependence of spin-lattice relaxation time at low temperatures.

Abstract

Within the two-leg $t$-J ladder, the spin dynamics of the pressure-induced two-leg ladder cuprate superconductor Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$ is studied based on the kinetic energy driven superconducting mechanism. It is shown that in the pressure-induced superconducting state, the incommensurate spin correlation appears in the underpressure regime, while the commensurate spin fluctuation emerges in the optimal pressure and overpressure regimes. In particular, the spin-lattice relaxation time is dominated by a temperature linear dependence term at low temperature followed by a peak developed below the superconducting transition temperature, in qualitative agreement with the experimental observation on Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$.