Unlike conventional magnets where the magnetic moments are partially or completely static in the ground state, in a quantum spin liquid they remain in collective motion down to the lowest temperatures. The importance of this state is that it is coherent and highly entangled without breaking local symmetries. Such phenomena is usually sought in simple lattices where antiferromagnetic interactions and/or anisotropies that favor specific alignments of the magnetic moments are "frustrated" by lattice geometries incompatible with such order e.g. triangular structures. Despite an extensive search among such compounds, experimental realizations remain very few. Here we describe the investigation of a novel, unexplored magnetic system consisting of strong ferromagnetic and weaker antiferromagnetic isotropic interactions as realized by the compound Ca10Cr7O28. Despite its exotic structure we show both experimentally and theoretically that it displays all the features expected of a quantum spin liquid including coherent spin dynamics in the ground state and the complete absence of static magnetism.
@article{arxiv.1606.06463,
title = {Physical realization of a quantum spin liquid based on a novel frustration mechanism},
author = {Christian Balz and Bella Lake and Johannes Reuther and Hubertus Luetkens and Rico Schönemann and Thomas Herrmannsdörfer and Yogesh Singh and A. T. M. Nazmul Islam and Elisa M. Wheeler and Jose A. Rodriguez-Rivera and Tatiana Guidi and Giovanna G. Simeoni and Chris Baines and Hanjo Ryll},
journal= {arXiv preprint arXiv:1606.06463},
year = {2016}
}