Spin dynamics in itinerant antiferromagnet SrCr$_2$As$_2$
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2024
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| author | Ning, Zhenhua Das, Pinaki Lee, Y. Sangeetha, N. S. Abernathy, Douglas L. Johnston, D. C. McQueeney, R. J. Vaknin, D. Ke, Liqin |
| author_facet | Ning, Zhenhua Das, Pinaki Lee, Y. Sangeetha, N. S. Abernathy, Douglas L. Johnston, D. C. McQueeney, R. J. Vaknin, D. Ke, Liqin |
| contents | SrCr$_2$As$_2$ is an itinerant antiferromagnet in the same structural family as the SrFe$_2$As$_2$ high-temperature superconductors. We report our calculations of exchange-coupling parameters $J_{ij}$ for SrCr$_2$As$_2$ using a static linear-response method based on first-principles electronic-structure calculations. We find that the dominant nearest-neighbor exchange coupling $J_{\rm{1}} > 0$ is antiferromagnetic whereas the next-nearest-neighbor interaction $J_{\rm{2}} < 0$ is ferromagnetic with $J_{\rm{2}}$/$J_{\rm{1}}$~=~$-0.68$, reinforcing the checkerboard in-plane magnetic structure. Thus, unlike other transition-metal arsenides based on Mn, Fe, or Co, we find no competing magnetic interactions in SrCr$_2$As$_2$, which aligns with experimental findings. Moreover, the orbital resolution of exchange interactions shows that $J_1$ and $J_2$ are dominated by direct exchange mediated by the Cr $d$ orbitals. To validate the calculations we conduct inelastic neutron-scattering measurements on powder samples that show steeply dispersive magnetic excitations arising from the magnetic $Γ$ points and persisting up to energies of at least 175 meV. The spin-wave spectra are then modeled using the Heisenberg Hamiltonian with the theoretically-calculated exchange couplings. The calculated neutron-scattering spectra are in good agreement with the experimental data. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2408_05583 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Spin dynamics in itinerant antiferromagnet SrCr$_2$As$_2$ Ning, Zhenhua Das, Pinaki Lee, Y. Sangeetha, N. S. Abernathy, Douglas L. Johnston, D. C. McQueeney, R. J. Vaknin, D. Ke, Liqin Superconductivity Materials Science SrCr$_2$As$_2$ is an itinerant antiferromagnet in the same structural family as the SrFe$_2$As$_2$ high-temperature superconductors. We report our calculations of exchange-coupling parameters $J_{ij}$ for SrCr$_2$As$_2$ using a static linear-response method based on first-principles electronic-structure calculations. We find that the dominant nearest-neighbor exchange coupling $J_{\rm{1}} > 0$ is antiferromagnetic whereas the next-nearest-neighbor interaction $J_{\rm{2}} < 0$ is ferromagnetic with $J_{\rm{2}}$/$J_{\rm{1}}$~=~$-0.68$, reinforcing the checkerboard in-plane magnetic structure. Thus, unlike other transition-metal arsenides based on Mn, Fe, or Co, we find no competing magnetic interactions in SrCr$_2$As$_2$, which aligns with experimental findings. Moreover, the orbital resolution of exchange interactions shows that $J_1$ and $J_2$ are dominated by direct exchange mediated by the Cr $d$ orbitals. To validate the calculations we conduct inelastic neutron-scattering measurements on powder samples that show steeply dispersive magnetic excitations arising from the magnetic $Γ$ points and persisting up to energies of at least 175 meV. The spin-wave spectra are then modeled using the Heisenberg Hamiltonian with the theoretically-calculated exchange couplings. The calculated neutron-scattering spectra are in good agreement with the experimental data. |
| title | Spin dynamics in itinerant antiferromagnet SrCr$_2$As$_2$ |
| topic | Superconductivity Materials Science |
| url | https://arxiv.org/abs/2408.05583 |