TY - JOUR
T1 - Controlling crystal-electric field levels through symmetry-breaking uniaxial pressure in a cubic super heavy fermion
AU - Gati, Elena
AU - Schmidt, Burkhard
AU - Bud’ko, Sergey L.
AU - Mackenzie, Andrew P.
AU - Canfield, Paul C.
N1 - Financial support by the Max Planck Society is gratefully acknowledged. In addition, we gratefully acknowledge funding through the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through TRR 288–422213477 (project A10) and the SFB 1143 (project-id 247310070; project C09). Research in Dresden benefits from the environment provided by the DFG Cluster of Excellence ct.qmat (EXC 2147, project ID 390858940). Work at the Ames National Laboratory was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The Ames National Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DEAC02-07CH11358.
PY - 2023/11/20
Y1 - 2023/11/20
N2 - 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 elastic level splitting that is unambiguously
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 ≈ 1.6 K above the doublet ground state at ambient pressure, is well below the proposed Kondo temperature TK ≈ 10 K.
Consequently, this analysis of the energy scheme can provide support
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.
AB - 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 elastic level splitting that is unambiguously
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 ≈ 1.6 K above the doublet ground state at ambient pressure, is well below the proposed Kondo temperature TK ≈ 10 K.
Consequently, this analysis of the energy scheme can provide support
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.
U2 - 10.1038/s41535-023-00596-1
DO - 10.1038/s41535-023-00596-1
M3 - Article
SN - 2397-4648
VL - 8
JO - npj Quantum Materials
JF - npj Quantum Materials
M1 - 69
ER -