Pressure-induced shift of effective Ce valence, Fermi energy and phase boundaries in CeOs$_4$Sb$_{12}$

K. Götze; M. J. Pearce; M. J. Coak; P. A. Goddard; A. D. Grockowiak; W. A. Coniglio; S. W. Tozer; D. E. Graf; M. B. Maple; P. -C. Ho; M. C. Brown; J. Singleton

doi:10.1088/1367-2630/ac643c

arXiv · 2112.03353

Pressure-induced shift of effective Ce valence, Fermi energy and phase boundaries in CeOs$_4$Sb$_{12}$

K. Götze·M. J. Pearce·M. J. Coak·P. A. Goddard·A. D. Grockowiak·W. A. Coniglio·S. W. Tozer·D. E. Graf·M. B. Maple·P. -C. Ho·M. C. Brown·J. Singleton

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Abstract

CeOs$_4$Sb$_{12}$, a member of the skutterudite family, has an unusual semimetallic low-temperature $\cal{L}$-phase that inhabits a wedge-like area of the field $H$ - temperature $T$ phase diagram. We have conducted measurements of electrical transport and megahertz conductivity on CeOs$_4$Sb$_{12}$ single crystals under pressures of up to 3 GPa and in high magnetic fields of up to 41 T to investigate the influence of pressure on the different $H$-$T$ phase boundaries. While the high-temperature valence transition between the metallic $\cal{H}$-phase and the $\cal{L}$-phase is shifted to higher $T$ by pressures of the order of 1 GPa, we observed only a marginal suppression of the $\cal{S}$-phase that is found below 1 K for pressures of up to 1.91 GPa. High-field quantum oscillations have been observed for pressures up to 3.0 GPa and the Fermi surface of the high-field side of the $\cal{H}$-phase is found to show a surprising decrease in size with increasing pressure, implying a change in electronic structure rather than a mere contraction of lattice parameters. We evaluate the field-dependence of the effective masses for different pressures and also reflect on the sample dependence of some of the properties of CeOs$_4$Sb$_{12}$ which appears to be limited to the low-field region.

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K. Götze, M. J. Pearce, M. J. Coak, P. A. Goddard, A. D. Grockowiak, W. A. Coniglio, S. W. Tozer, D. E. Graf, M. B. Maple, P. -C. Ho, M. C. Brown, J. Singleton. 2021-12-06. Pressure-induced shift of effective Ce valence, Fermi energy and phase boundaries in CeOs$_4$Sb$_{12}$. https://doi.org/10.1088/1367-2630/ac643c

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