New Article in Science: Gapped magnetic ground state in quantum spin liquid candidate

physicsworld published an article about our publication in Science:

7 May 2021 Isabelle Dumé

Please read the article:

Promising quantum spin liquid candidate may fall short

https://physicsworld.com/a/promising-quantum-spin-liquid-candidate-may-fall-short/

Please read the article in The Academic Times:

https://academictimes.com/two-decade-disagreement-on-quantum-spin-liquids-put-to-rest-with-new-findings/

New Article in Science:

Björn Miksch, Andrej Pustogow, Mojtaba Javaheri Rahim, Andrey A. Bardin, Kazushi Kanoda, John A. Schlueter, Ralph Hübner, Marc Scheffler, Martin Dressel

Gapped magnetic ground state in quantum spin liquid candidate ĸ-(BEDT-TTF)₂Cu₂(CN)₃

Geometrical frustration, quantum entanglement, and disorder may prevent long-range ordering of localized spins with strong exchange interactions, resulting in an exotic state of matter. k-(BEDT-TTF)₂Cu₂(CN)₃ is considered the prime candidate for this elusive quantum spin liquid state, but its ground-state properties remain puzzling. We present a multifrequency electron spin resonance (ESR) study down to millikelvin temperatures, revealing a rapid drop of the spin susceptibility at 6 kelvin. This opening of a spin gap, accompanied by structural modifications, is consistent with the formation of a valence bond solid ground state. We identify an impurity contribution to the ESR response that becomes dominant when the intrinsic spins form singlets. Probing the electrons directly manifests the pivotal role of defects for the low-energy properties of quantum spin systems without magnetic order.