Magnetisation of hole-doped CuO2 spin chains in Sr14-xCaxCu24O41

TL;DR

This study investigates how Ca-doping affects the magnetic properties of Sr14-xCaxCu24O41, revealing a doping-dependent linear magnetisation component likely linked to hole dynamics in CuO2 spin chains.

Contribution

It provides new insights into the doping-dependent magnetic response and suggests hole dynamics influence magnetisation beyond simple antiferromagnetic chain models.

Findings

Doping reduces hole concentration in CuO2 chains.

Linear magnetisation component increases with Ca content.

Hole dynamics may play a role in magnetic behaviour.

Abstract

We report on magnetisation measurements of Sr14-xCaxCu24O41, with 0 <= x <= 12, in magnetic fields up to 16 T. The low temperature magnetic response of the CuO2 spin chains changes strongly upon doping. For x = 0, the ground state with nearly independent dimers is confirmed. Reduction of the number of holes in the chains through Ca-doping leads to an additional contribution to the magnetisation, which depends linearly on the magnetic field. Remarkably, the slope of this linear contribution increases with the Ca content. We argue that antiferromagnetic spin chains do not account for this behaviour but that the hole dynamics might be involved.