The organic material was previously thought to be one of the best examples of a two-dimensional triangular-lattice quantum spin liquid.

Quantum spin liquids are systems that avoid magnetic ordering, despite strong magnetic interactions, due to the effects of quantum fluctuations. Such materials are being sought intensively by scientists as platforms for studying quantum entanglement in the solid state, with potential applications in the field of quantum computing.

Using muon spectroscopy measurements from the ARGUS instrument within the RIKEN-RAL facility at ISIS, combined with electron paramagnetic resonance studies carried out at RIKEN and further muon studies on HiFi and at PSI, the researchers were able to show that, due to an interesting effect known as dimensional reduction, the material b'‑EtMe₃Sb[Pd(dmit)₂]₂ is actually a one dimensional quantum spin liquid. 

Attempts to analyse the previous measurements on this material under the assumption that it was a two-dimensional quantum spin liquid had led to contradictory results, but the new insight offered by the latest study includes improved theoretical calculations of the magnetic interactions and their variation with direction. These experimental and theoretical advances togeth​er provide a clearer understanding of the properties of this system and an explanation for the apparent inconsistencies found in previous results. 

The full paper is now online at DOI: 10.1103/PhysRevLett.133.236702

Image caption: Left: crystal structure of β′−EtMe3Sb[Pd(dmit)₂]₂. Two crystallographically equivalent Pd(dmit)₂ layers with different dimer stacking directions exist in the unit cell (layers A and B), and the Pd(dmit)₂ dimer with S=1/2 forms a triangular lattice in each layer. Right: schematic drawings of the triangular lattice and its transfer integrals for layers A and B. θ is the angle of the magnetic field from the a axis used for ESR.​​