Divergent effects of static disorder and hole doping in geometrically frustrated b-CaCr2O4

TL;DR

This study compares how static disorder from Ga substitution and hole doping from calcium deficiency differently affect magnetic frustration and ordering in the geometrically frustrated magnet b-CaCr2O4.

Contribution

It provides a direct comparison of static disorder and hole doping effects on magnetic properties in a frustrated magnet, revealing distinct impacts on magnetic frustration and ordering.

Findings

Ga substitution gradually releases spins from antiferromagnetic order

Hole doping induces static ferrimagnetic order and stronger perturbations

Both types of disorder reduce magnetic frustration

Abstract

The gallium substituted and calcium deficient variants of geometrically frustrated b-CaCr2O4, b-CaCr2-2xGa2xO4 (0.02<= x<= 0.25) and b-Ca1-yCr2O4 (0.075<= y<= 0.15), have been investigated by x-ray powder diffraction, magnetization and specific heat measurements. This allows for a direct comparison of the effects, in a geometrically frustrated magnet, of the static disorder that arises from non-magnetic substitution and the dynamic disorder that arises from hole doping. In both cases, disturbing the Cr3+ lattice results in a reduction in the degree of magnetic frustration. On substitution of Ga, which introduces disorder without creating holes, a gradual release of spins from ordered antiferromagnetic states is observed. In contrast, in the calcium deficient compounds the introduction of holes induces static ferrimagnetic ordering and much stronger perturbations of the b-CaCr2O4 host.