Evidence for a Parity Broken Monoclinic Ground State in the S = 1/2 Kagomé Antiferromagnet Herbertsmithite

Abstract

Nearest-neighbor interacting S = 1/2 spins on the ideal Kagomé lattice are predicted to form a variety of novel quantum entangled states, including quantum spin-liquid (SL) and valence bond solid (VBS) phases. In real materials, the presence of additional perturbative spin interactions may further expand the variety of entangled states, which recent theoretical analyses show are identifiable through the spontaneous loss of particular discrete point group symmetries. Here we comprehensively resolve the ground state point group symmetries of the prototypical Kagomé SL candidate ZnCu${}_3$(OH)${}_6$Cl${}_2$ (Herbertsmithite) using a combination of optical ellipsometry and wavelength-dependent multi-harmonic optical polarimetry. We uncover a subtle parity breaking monoclinic structural distortion at a temperature above the nearest-neighbor exchange energy scale. Surprisingly, the parity-breaking order parameter is dramatically enhanced upon cooling and closely tracks the build-up of nearest-neighbor spin correlations, suggesting that it is energetically favored by the SL state. The refined low temperature symmetry group greatly restricts the number of viable ground states, and, in the perturbative limit, points toward the formation of a nematic $Z_2$ striped SL ground state - a SL analogue of a liquid crystal.

arXiv comment13 pages main text, 4 figures, 10 pages supplementary information

References in corpus (22)

• Spin Liquid Ground State of the $S=1/2$ Kagome Heisenberg Model
• Fractionalized excitations in the spin liquid state of a kagomé lattice antiferromagnet
• Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2
• Herbertsmithite and the Search for the Quantum Spin Liquid
• Spin Driven Jahn-Teller Distortion in a Pyrochlore system
• Dirac, Anderson, and Goldstone on the Kagome
• Dzyaloshinsky-Moriya Anisotropy in the Spin-1/2 Kagomé Compound ZnCu${}_3$(OH)${}_6$Cl${}_2$
• Quantum phase transition induced by Dzyaloshinskii-Moriya in the kagome antiferromagnet
• Frustrated antiferromagnets with entanglement renormalization: ground state of the spin-1/2 Heisenberg model on a kagome lattice
• The kagome antiferromagnet: a chiral topological spin liquid ?
• Correlated impurities and intrinsic spin liquid physics in the kagome material Herbertsmithite
• Spin-Peierls phases in pyrochlore antiferromagnets
• Dynamic Scaling in the Susceptibility of the Spin-1\2 Kagome Lattice Antiferromagnet Herbertsmithite
• First-principles determination of Heisenberg Hamiltonian parameters for the spin-1/2 kagome antiferromagnet ZnCu3(OH)6Cl2
• Refining the Spin Hamiltonian in the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu${}_3$(OH)${}_6$Cl${}_2$ using Single Crystals
• Synthesis and Characterization of Single Crystal Samples of Spin-$1/2$ Kagome Lattice Antiferromagnets in the Zn-Paratacamite Family Zn${}_x$Cu${}_{4-x}$(OH)${}_6$Cl${}_2$
• Symmetry Reduction in the Quantum Kagome Antiferromagnet Herbertsmithite
• Chiral spin liquids on the kagome Lattice
• Striped spin liquid crystal ground state instability of kagome antiferromagnets
• Gapless Spin Liquids: Stability and Possible Experimental Relevance
• ${\mathbb{Z}}_2$ gauge theory for valence bond solids on the kagome lattice
• Thermodynamics of the kagome-lattice Heisenberg antiferromagnet with arbitrary spin $S$

Cited by in corpus (6)

• Phase diagram of a distorted kagome antiferromagnet and application to Y-kapellasite
• Origin of Magnetic Ordering in a Structurally-Perfect Quantum Kagome Antiferromagnet
• Dynamic fingerprint of fractionalized excitations in single-crystalline Cu${}_3$Zn(OH)${}_6$FBr
• Site-Specific Structure at Multiple Length Scales in Kagome Quantum Spin Liquid Candidates
• Specific Heat of the Kagome Antiferromagnet Herbertsmithite in High Magnetic Fields
• Lattice dynamics in the spin-1/2 frustrated kagome compound herbertsmithite