Controlled Frustration Release on the Kagome Lattice by Uniaxial-Strain Tuning

Abstract

It is predicted that strongly interacting spins on a frustrated lattice may lead to a quantum disordered ground state or even form a quantum spin liquid with exotic low-energy excitations. However, a controlled tuning of the frustration strength, separating its effects from those of disorder and other factors, is pending. Here, we perform comprehensive 1H NMR measurements on Y3Cu9(OH)19Cl8 single crystals revealing an unusual →Q=(1/3×1/3) antiferromagnetic state below TN=2.2 K. By applying in situ uniaxial stress, we break the symmetry of this disorder-free, frustrated kagome system in a controlled manner yielding a linear increase of TN with strain, in line with theoretical predictions for a distorted kagome lattice. In-plane strain of ≈1% triggers a sizable enhancement ΔTN/TN≈10% due to a release of frustration, demonstrating its pivotal role for magnetic order.