Quantum spin liquids (QSL) are a highly entangled state, which precludes any long-range ordering down to even absolute zero temperature. It hosts topologically protected fractionalized excitations, i.e., Majorana fermions, which hold great potential for quantum communication and computation. The Kitaev model for QSL is exactly solvable for spin-1/2, whereas high-spin systems mostly remain unexplored. Here we present a comprehensive thickness (down to ∼8–9 layers) dependent inelastic Raman spectroscopic measurement on a single crystal of ${\mathrm{V}}_{0.85}{\mathrm{PS}}_3$, a proximate QSL candidate. The presence of phonon anomalies in energies, broadening of linewidth, and finally the Fano asymmetry of low-energy phonon modes is attributed to the decay of phonons into itinerant Majorana fermions deep into the paramagnetic region starting from the cross-over temperature at ∼200 K. Further, this observation is supported by the qualitative analysis of the underlying broad magnetic continuum which increases significantly with decreasing thickness, quasielastic scattering gauzed via Raman response, and dynamic Raman susceptibility ${\chi }^{\mathrm{dyn}}$. The inappreciable effect of the long-range antiferromagnetic ordering in flakes as compared to the bulk suggests enhanced quantum fluctuation in the low-dimensional regime and, as a result, prominent QSL state effect. Our results set a new paradigm in the field of atomically thin quasi-2D magnets and future quantum materials.

Close

PrevNext

View figure in article

• Quantum spin liquid
• 2-dimensional systems
• Magnetic insulators
• Density functional theory
• Raman spectroscopy