Violation of Ioffe-Regel condition but saturation of resistivity of the high Tc cuprates

TL;DR

This paper shows that high Tc cuprates exhibit resistivity saturation despite violating the Ioffe-Regel condition, due to strong correlations reducing kinetic energy, leading to unusually high saturation resistivity.

Contribution

It provides a theoretical explanation for resistivity saturation in high Tc cuprates, challenging the conventional Ioffe-Regel criterion through sum rule and kinetic energy calculations.

Findings

Resistivity saturation occurs in high Tc cuprates despite Ioffe-Regel violation.

Saturation resistivity is unusually large due to reduced kinetic energy.

Ioffe-Regel condition's applicability is accidental in transition metals.

Abstract

We demonstrate that the resistivity data of a number of high Tc cuprates, in particular La(2-x)SrxCuO4, are consistent with resistivity saturation, although the Ioffe-Regel condition is strongly violated. By using the f-sum rule together with calculations of the kinetic energy in the t-J model, we show that the saturation resistivity is unusually large. This is related to the strong reduction of the kinetic energy due to strong correlation effects. The fulfilment of the Ioffe-Regel condition for conventional transition metal compounds is found to be somewhat accidental.