Elastocaloric effect of the heavy-fermion system YbPtBi
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2023-03-15
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arXiv
Abstract
YbPtBi is one of the heavy-fermion systems with largest Sommerfeld coefficient γ and is thus classified as a `super'-heavy fermion material. In this work, we resolve the long-debated question about the hierarchy of relevant energy scales, such as crystal-electric field (CEF) levels, Kondo and magnetic ordering temperature, in YbPtBi. Through measurements of the a.c. elastocaloric effect and generic symmetry arguments, we identify an \textit{elastic level splitting} that is uniquely associated with the symmetry-allowed splitting of a quartet CEF level. This quartet, which we identify to be the first excited state at Δ/kB≈1.6K above the doublet ground state at ambient pressure, is well below the Kondo temperature TK≈10K. Thus, our analysis provides strong support for models that predict that the heavy electron mass is a result of an enhanced degeneracy of the CEF ground state, i.e., a quasi-sextet in YbPtBi. At the same time, our study shows the potential of the a.c. elastocaloric effect to control and quantify strain-induced changes of the CEF schemes, opening a different route to disentangle the CEF energy scales from other relevant energy scales in correlated quantum materials.
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preprint
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This is a pre-print of the article Gati, Elena, Burkhard Schmidt, Sergey L. Bud'ko, Andrew P. Mackenzie, and Paul C. Canfield. "Elastocaloric effect of the heavy-fermion system YbPtBi." arXiv preprint arXiv:2303.08770 (2023).
DOI: 10.48550/arXiv.2303.08770.
Attribution 4.0 International (CC BY 4.0).
Copyright 2023 The Authors.
Posted with permission.