Pinwheel VBS state and triplet excitations in the two-dimensional deformed kagome lattice

TL;DR

This paper reports the experimental realization of a pinwheel valence bond solid ground state in a deformed kagome lattice antiferromagnet, demonstrating how lattice distortion stabilizes this quantum spin state in a highly frustrated system.

Contribution

First experimental observation of the pinwheel VBS state in a deformed kagome lattice, confirming theoretical predictions about quantum spin states in frustrated systems.

Findings

Identification of the pinwheel VBS ground state in Rb2Cu3SnF12

Lattice distortion stabilizes the VBS state

Observation of quantum spin state in a highly frustrated lattice

Abstract

Determining ground states of correlated electron systems is fundamental to understanding novel phenomena in condensed matter physics. A difficulty, however, arises in a geometrically frustrated system in which the incompatibility between the global topology of an underlying lattice and local spin interactions gives rise to macroscopically degenerate ground states, potentially prompting the emergence of quantum spin states, such as resonating valence bond (RVB) and valence bond solid (VBS). Although theoretically proposed to exist in a kagome lattice -- one of the most highly frustrated lattices in two dimensions (2D) being comprised of corner-sharing triangles -- such quantum-fluctuation-induced states have not been observed experimentally. Here we report the first realization of the "pinwheel" VBS ground state in the S=1/2 deformed kagome lattice antiferromagnet Rb2Cu3SnF12. In this system, a lattice distortion breaks the translational symmetry of the ideal kagome lattice and stabilizes the VBS state.