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arXiv · 1510.07416

Neutron spectroscopic study of crystal-field excitations and the effect of the crystal field on dipolar magnetism in Li$R$F$_4$ ($R$ = Gd, Ho, Er, Tm, and Yb)

P. Babkevich·A. Finco·M. Jeong·B. Dalla Piazza·I. Kovacevic·G. Klughertz·K. W. Krämer·C. Kraemer·D. T. Adroja·E. Goremychkin·T. Unruh·T. Strässle·A. Di Lieto·J. Jensen·H. M. Rønnow
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Abstract

We present a systematic study of the crystal field interactions in the Li$R$F$_4$, $R$ = Gd, Ho, Er, Tm and Yb, family of rare-earth magnets. Using detailed inelastic neutron scattering measurements we have been able to quantify the transition energies and wavefunctions for each system. This allows us to quantitatively describe the high-temperature susceptibility measurements for the series of materials and make predictions based on a mean-field approach for the low-temperature thermal and quantum phase transitions. We show that coupling between crystal field and phonon states leads to lineshape broadening in LiTmF$_4$ and level splitting in LiYbF$_4$. Furthermore, using high resolution neutron scattering from LiHoF$_4$, we find anomalous broadening of crystal-field excitations which we attribute to magnetoelastic coupling.

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P. Babkevich, A. Finco, M. Jeong, B. Dalla Piazza, I. Kovacevic, G. Klughertz, K. W. Krämer, C. Kraemer, D. T. Adroja, E. Goremychkin, T. Unruh, T. Strässle, A. Di Lieto, J. Jensen, H. M. Rønnow. 2015-10-26. Neutron spectroscopic study of crystal-field excitations and the effect of the crystal field on dipolar magnetism in Li$R$F$_4$ ($R$ = Gd, Ho, Er, Tm, and Yb). https://doi.org/10.1103/physrevb.92.144422

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