Unraveling the magnetic ground-state in alkali-metal lanthanide oxide Na$_2$PrO$_3$
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2024
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| author | Onuorah, Ifeanyi John Frassineti, Jonathan Wang, Qiaochu Isah, Muhammad Maikudi Bonfa, Pietro Rau, Jeffrey G. Rodriguez-Rivera, J. A. Kolesnikov, A. I. Mitrovic, Vesna F. Sanna, Samuele Plumb, Kemp W. |
| author_facet | Onuorah, Ifeanyi John Frassineti, Jonathan Wang, Qiaochu Isah, Muhammad Maikudi Bonfa, Pietro Rau, Jeffrey G. Rodriguez-Rivera, J. A. Kolesnikov, A. I. Mitrovic, Vesna F. Sanna, Samuele Plumb, Kemp W. |
| contents | A comprehensive set of muon spin spectroscopy and neutron scattering measurements supported by ab-initio and model Hamiltonian simulations have been used to investigate the magnetic ground state of Na$_2$PrO$_3$. $μ$SR reveals Néel antiferromagnetic order below $T_{\rm N}\! \sim\! 4.9$ K, with a small static magnetic moment $m_{\rm static}\!\leq \! 0.22$~$μ_{\rm B}/{\rm Pr}$ collinearly aligned along the $c-$axis. Inelastic neutron measurements reveal the full spectrum of crystal field excitations and confirm that the Pr$^{4+}$ ground state wave function deviates significantly from the $Γ_7$ limit relevant to the Kitaev model. Single and two magnon excitations are observed in the ordered state below $T_N=4.6$ K and are well described by non-linear spin wave theory from the Néel state using a magnetic Hamiltonian with Heisenberg exchange $J=1$ meV and symmetric anisotropic exchange $Γ/J=0.1$, corresponding to an XY model. Intense two magnon excitations are accounted for by $g$-factor anisotropy $g_\mathrm{z}/g_\pm = 1.29$. A fluctuating moment $δm^2 = 0.57(22)$ $μ_{\rm B}^2/{\rm Pr}$ extracted from the energy and momentum integrated inelastic neutron signal is reduced from expectations for a local $J=1/2$ moment with average $g$-factor $g_{\rm avg}\approx 1.1$. Together, the results demonstrate that the small moment in Na$_2$PrO$_3$ arises from crystal field and covalency effects and that the material does not exhibit significant quantum fluctuations.. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2407_12935 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Unraveling the magnetic ground-state in alkali-metal lanthanide oxide Na$_2$PrO$_3$ Onuorah, Ifeanyi John Frassineti, Jonathan Wang, Qiaochu Isah, Muhammad Maikudi Bonfa, Pietro Rau, Jeffrey G. Rodriguez-Rivera, J. A. Kolesnikov, A. I. Mitrovic, Vesna F. Sanna, Samuele Plumb, Kemp W. Strongly Correlated Electrons A comprehensive set of muon spin spectroscopy and neutron scattering measurements supported by ab-initio and model Hamiltonian simulations have been used to investigate the magnetic ground state of Na$_2$PrO$_3$. $μ$SR reveals Néel antiferromagnetic order below $T_{\rm N}\! \sim\! 4.9$ K, with a small static magnetic moment $m_{\rm static}\!\leq \! 0.22$~$μ_{\rm B}/{\rm Pr}$ collinearly aligned along the $c-$axis. Inelastic neutron measurements reveal the full spectrum of crystal field excitations and confirm that the Pr$^{4+}$ ground state wave function deviates significantly from the $Γ_7$ limit relevant to the Kitaev model. Single and two magnon excitations are observed in the ordered state below $T_N=4.6$ K and are well described by non-linear spin wave theory from the Néel state using a magnetic Hamiltonian with Heisenberg exchange $J=1$ meV and symmetric anisotropic exchange $Γ/J=0.1$, corresponding to an XY model. Intense two magnon excitations are accounted for by $g$-factor anisotropy $g_\mathrm{z}/g_\pm = 1.29$. A fluctuating moment $δm^2 = 0.57(22)$ $μ_{\rm B}^2/{\rm Pr}$ extracted from the energy and momentum integrated inelastic neutron signal is reduced from expectations for a local $J=1/2$ moment with average $g$-factor $g_{\rm avg}\approx 1.1$. Together, the results demonstrate that the small moment in Na$_2$PrO$_3$ arises from crystal field and covalency effects and that the material does not exhibit significant quantum fluctuations.. |
| title | Unraveling the magnetic ground-state in alkali-metal lanthanide oxide Na$_2$PrO$_3$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2407.12935 |