Interplay of disorder and geometrical frustration in doped Gadolinium Gallium Garnet

TL;DR

This study explores how minimal Neodymium doping influences the magnetic frustration and local spin structures in Gadolinium Gallium Garnet, revealing that disorder enhances frustration and clarifies the nature of spin clusters at very low temperatures.

Contribution

It demonstrates that small amounts of Nd doping increase magnetic frustration and isolate quantum states, providing new insights into disorder's role in geometrically frustrated magnets.

Findings

Doping enhances magnetic frustration in GGG.

Disorder promotes more perfect frustration and isolates quantum states.

Optical data supports increased frustration with doping.

Abstract

The geometrically-frustrated, triangular antiferromagnet GGG exhibits a rich mix of short-range order and isolated quantum states. We investigate the effects of up to 1% Neodymium substitution for Gallium on the ac magnetic response at temperatures below 1 K in both the linear and nonlinear regimes. Substitutional disorder actually drives the system towards a more perfectly frustrated state, apparently compensating for the effect of imperfect Gadolinium/Gallium stoichiometry, while at the same time more closely demarcating the boundaries of isolated, coherent clusters composed of hundreds of spins. Optical measurements of the local Nd environment substantiate the picture of an increased frustration index with doping.