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arXiv · 2011.00606

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

Srishti Pal·Arnab Seth·Piyush Sakrikar·Anzar Ali·Subhro Bhattacharjee·D. V. S. Muthu·Yogesh Singh·A. K. Sood
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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.

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Srishti Pal, Arnab Seth, Piyush Sakrikar, Anzar Ali, Subhro Bhattacharjee, D. V. S. Muthu, Yogesh Singh, A. K. Sood. 2020-11-01. Probing signatures of fractionalization in candidate quantum spin liquid Cu2IrO3 via anomalous Raman scattering. https://doi.org/10.1103/physrevb.104.184420

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