Probing signatures of fractionalization in candidate quantum spin liquid Cu2IrO3 via anomalous Raman scattering

Abstract

Long-range entanglement in quantum spin liquids (QSLs) lead to novel low energy excitations with fractionalised quantum numbers and (in 2D) statistics. Experimental detection and manipulation of these excitations present a challenge particularly in view of diverse candidate magnets. A promising probe of fractionalisation is their coupling to phonons. Here we present Raman scattering results for the S = 1/2 honeycomb iridate Cu2IrO3, a candidate Kitaev QSL with fractionalised Majorana fermions and Ising flux excitations. We observe anomalous low temperature frequency shift and linewidth broadening of the Raman intensities in addition to a broad magnetic continuum both of which, we derive, are naturally attributed to the phonon decaying into itinerant Majoranas. The dynamic Raman susceptibility marks a crossover from the QSL to a thermal paramagnet at ~120 K. The phonon anomalies below this temperature demonstrate a strong phonon-Majorana coupling. These results provide for evidence of spin fractionalisation in Cu2IrO3.

arXiv comment17 figures, 2 tables

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Cited by in corpus (12)

• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Phonon Dynamics in the Generalized Kitaev Spin Liquid
• Pressure tuning of structure, magnetic frustration and carrier conduction in Kitaev spin liquid candidate Cu${}_2$IrO${}_3$: X-ray, Raman, magnetic susceptibility, resistivity and first-principles analysis
• Fluctuating Fractionalized Spins in Quasi Two-dimensional Magnetic V0.85PS3
• Quantum many-body scars in spin-1 Kitaev chain with uniaxial single-ion anisotropy
• Raman fingerprints of fractionalized Majorana excitations in honeycomb iridate Ag${}_3$LiIr${}_2$O${}_6$
• High-temperature magnetic anomaly via suppression of antisite disorder through synthesis route modification in a Kitaev candidate Cu${}_2$IrO${}_3$
• Probing emergent QED in quantum spin ice via Raman scattering of phonons: shallow inelastic scattering and pair production
• Sound attenuation in the hyperhoneycomb Kitaev spin liquid
• Potential of Raman scattering in probing magnetic excitations and their coupling to lattice dynamics
• Phonon anomalies and critical scaling in the spin-$1/2$ trimer chain Na${}_2$Cu${}_3$Ge${}_4$O${}_{12}$
• Magnetic-field induced melting of long-range magnetic order akin to Kitaev insulators in the metallic compound Tb5Si3