Instabilities of Spin-Liquid States in a Quantum Kagome Antiferromagnet

TL;DR

This paper investigates the complex behavior of spin-liquid states in a quantum kagome antiferromagnet, revealing multiple fluctuating phases and instabilities that deepen understanding of geometrically frustrated quantum magnets.

Contribution

It demonstrates the existence of multiple correlated spin-liquid states and their transitions in a quantum kagome antiferromagnet using combined experimental techniques.

Findings

Discovery of a crossover to a gapless spin-liquid phase

Identification of an unconventional instability leading to a second spin-liquid state

Observation of complex fluctuating states in frustrated quantum magnets

Abstract

The emergent behavior of spin liquids that are born out of geometrical frustration makes them an intriguing state of matter. We show that in the quantum kagome antiferromagnet ZnCu$_3$(OH)$_6$SO$_4$ several different correlated, yet fluctuating states exist. By combining complementary local-probe techniques with neutron scattering, we discover a crossover from a critical regime into a gapless spin-liquid phase with decreasing temperature. An additional unconventional instability of the latter phase leads to a second, distinct spin-liquid state that is stabilized at the lowest temperatures. We advance such complex behavior as a feature common to different frustrated quantum magnets.