Macroscopic Signature of Protected Spins in a Dense Frustrated Magnet

Abstract

The inability of systems of interacting objects to satisfy all constraints simultaneously leads to frustration. A particularly important consequence of frustration is the ability to access certain protected parts of a system without disturbing the others. For magnets such "protectorates" have been inferred from theory and from neutron scattering, but their practical consequences have been unclear. We show that a magnetic analogue of optical hole-burning can address these protected spin clusters in a well-known, geometrically-frustrated Heisenberg system, Gadolinium Gallium Garnet. Our measurements additionally provide a resolution of a famous discrepancy between the bulk magnetometry and neutron diffraction results for this magnetic compound.

Dynamics in many-body localized quantum systems without disorder

“…The simplest experimental realizations, in which to observe the phenomenology described here, are strongly interacting cold atomic gases in one-dimensional optical lattices [28,29] or highly anisotropic spin chains and ladders, whose localization properties could be probed via hole burning techniques [34].…”

Hidden order in spin-liquid Gd 3 Ga 5 O 12

“…Each Gd 3+ also sits in the middle of exactly one loop; hence loop and atom share the same point symmetry and the local axes defined for atoms apply equally to loops. In a simple model which considers only nearest-neighbour antiferromagnetic interactions, collective rotations of the loop spins allow the system to move at no energy cost between its degenerate ground states (22). We therefore anticipate that the ten-spin loops should play a key role in any emergent behaviour present in the spin-liquid state.…”

Dispersionless Spin Waves and Underlying Field-Induced Magnetic Order in Gadolinium Gallium Garnet

“…However, this high field phase shows remarkable properties. In particular it has, as lowest lying spin wave excitations, almost dispersionless bands corresponding to excitations localized on ten site rings [1,14]. The magnetic field couples to these excitations via the Zeeman energy and hence contributes to the chemical potential for the (weakly interacting) spin waves.…”