Spin-orbit coupling in a half-filled $t_{2g}$ shell: the case of $5d^3$ K$_2$ReCl$_6$
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| Main Authors: | , , , , , , , , , , , |
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| Format: | Preprint |
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2023
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| author | Warzanowski, P. Magnaterra, M. Schlicht, G. Faure, Q. Sahle, Ch. J. Becker, P. Bohatý, L. Sala, M. Moretti Monaco, G. Hermanns, M. van Loosdrecht, P. H. M. Grüninger, M. |
| author_facet | Warzanowski, P. Magnaterra, M. Schlicht, G. Faure, Q. Sahle, Ch. J. Becker, P. Bohatý, L. Sala, M. Moretti Monaco, G. Hermanns, M. van Loosdrecht, P. H. M. Grüninger, M. |
| contents | The half-filled $t_{2g}$ shell of the $t_{2g}^3$ configuration usually, in LS coupling, hosts a S = 3/2 ground state with quenched orbital moment. This state is not Jahn-Teller active. Sufficiently large spin-orbit coupling $ζ$ has been predicted to change this picture by mixing in orbital moment, giving rise to a sizable Jahn-Teller distortion. In $5d^3$ K$_2$ReCl$_6$ we study the electronic excitations using resonant inelastic x-ray scattering (RIXS) and optical spectroscopy. We observe on-site intra-$t_{2g}$ excitations below 2 eV and corresponding overtones with two intra-$t_{2g}$ excitations on adjacent sites, the Mott gap at 2.7 eV, $t_{2g}$-to-$e_g$ excitations above 3 eV, and charge-transfer excitations at still higher energy. The intra-$t_{2g}$ excitation energies are a sensitive measure of $ζ$ and Hund's coupling $J_H$. The sizable value of $ζ\approx$ 0.29 eV places K$_2$ReCl$_6$ into the intermediate coupling regime, but $ζ/J_H \approx 0.6$ is not sufficiently large to drive a pronounced Jahn-Teller effect. We discuss the ground state wavefunction in a Kanamori picture and find that the S = 3/2 multiplet still carries about 97 % of the weight. However, the finite admixture of orbital moment allows for subtle effects. We discuss small temperature-induced changes of the optical data and find evidence for a lowering of the ground state by about 3 meV below the structural phase transitions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2311_11419 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Spin-orbit coupling in a half-filled $t_{2g}$ shell: the case of $5d^3$ K$_2$ReCl$_6$ Warzanowski, P. Magnaterra, M. Schlicht, G. Faure, Q. Sahle, Ch. J. Becker, P. Bohatý, L. Sala, M. Moretti Monaco, G. Hermanns, M. van Loosdrecht, P. H. M. Grüninger, M. Strongly Correlated Electrons The half-filled $t_{2g}$ shell of the $t_{2g}^3$ configuration usually, in LS coupling, hosts a S = 3/2 ground state with quenched orbital moment. This state is not Jahn-Teller active. Sufficiently large spin-orbit coupling $ζ$ has been predicted to change this picture by mixing in orbital moment, giving rise to a sizable Jahn-Teller distortion. In $5d^3$ K$_2$ReCl$_6$ we study the electronic excitations using resonant inelastic x-ray scattering (RIXS) and optical spectroscopy. We observe on-site intra-$t_{2g}$ excitations below 2 eV and corresponding overtones with two intra-$t_{2g}$ excitations on adjacent sites, the Mott gap at 2.7 eV, $t_{2g}$-to-$e_g$ excitations above 3 eV, and charge-transfer excitations at still higher energy. The intra-$t_{2g}$ excitation energies are a sensitive measure of $ζ$ and Hund's coupling $J_H$. The sizable value of $ζ\approx$ 0.29 eV places K$_2$ReCl$_6$ into the intermediate coupling regime, but $ζ/J_H \approx 0.6$ is not sufficiently large to drive a pronounced Jahn-Teller effect. We discuss the ground state wavefunction in a Kanamori picture and find that the S = 3/2 multiplet still carries about 97 % of the weight. However, the finite admixture of orbital moment allows for subtle effects. We discuss small temperature-induced changes of the optical data and find evidence for a lowering of the ground state by about 3 meV below the structural phase transitions. |
| title | Spin-orbit coupling in a half-filled $t_{2g}$ shell: the case of $5d^3$ K$_2$ReCl$_6$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2311.11419 |