Multilayer Crystal Field states from locally broken centrosymmetry

TL;DR

This paper uses polarized Raman spectroscopy to reveal complex crystal-electric-field states in CeCoSi, demonstrating entanglement of CEF states across layers due to local centrosymmetry breaking, suggesting new avenues for quantum order formation.

Contribution

It provides experimental evidence for interlayer entanglement of CEF states in a locally non-centrosymmetric compound, expanding understanding of quantum orders in such systems.

Findings

More CEF excitations observed than local models predict

Evidence of interlayer entanglement of CEF states

Potential for novel quantum orders in locally broken centrosymmetry systems

Abstract

Local charge, spin, or orbital degrees of freedom with intersite interactions are oftentimes sufficient to construct most quantum orders. This is conventionally true for f-electron systems, where the extent of the f-electrons and their associated crystal-electric-field (CEF) states are strongly localized. Here, polarized Raman spectroscopy measurements of a locally non-centrosymmetric compound, CeCoSi, unveil more CEF excitations than expected in the local model. We interpret this as experimental evidence for the entanglement of CEF states between cerium layers. This composite sublattice, spin, and orbital degree of freedom provides an unconsidered means to form novel orders, not only in this system, but in any system exhibiting globally preserved yet locally broken centrosymmetry.