Tunneling maps, non-monotonic resistivity, and non Drude optics in EuB$_6$
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arXiv
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| Autores principales: | , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866910559051448320 |
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| author | Mondal, Tanmoy Majumdar, Pinaki |
| author_facet | Mondal, Tanmoy Majumdar, Pinaki |
| contents | For several decades the low carrier density local moment magnet EuB$_6$ has been considered a candidate material for ferromagnetic polarons. There is however no consistent explanation for the host of intriguing observations that have accrued over the years, including a prominently non-monotonic resistivity near $T_c$, and observation of spatial textures, with a characteristic spatial and energy scale, via scanning tunneling spectroscopy. We resolve all these features using a Heisenberg-Kondo lattice model for EuB$_6$, solved using exact diagonalisation based Langevin dynamics. Over a temperature window $\sim 0.7T_c - 1.5T_c$ we observe electronic and magnetic textures with the correct spatial and energy scale, and confirm an associated non-monotonic resistivity. We predict a distinctly `non Drude' optical conductivity in the polaronic phase, and propose a field-temperature phase diagram testable through spin resolved tunneling spectroscopy. We argue that the anomalous properties of EuB$_6$, and magnetic polaron materials in general, occur due to a non monotonic change in spatial character of `near Fermi level' eigenstates with temperature, and the appearance of a weak pseudogap near $T_c$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_03628 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Tunneling maps, non-monotonic resistivity, and non Drude optics in EuB$_6$ Mondal, Tanmoy Majumdar, Pinaki Strongly Correlated Electrons For several decades the low carrier density local moment magnet EuB$_6$ has been considered a candidate material for ferromagnetic polarons. There is however no consistent explanation for the host of intriguing observations that have accrued over the years, including a prominently non-monotonic resistivity near $T_c$, and observation of spatial textures, with a characteristic spatial and energy scale, via scanning tunneling spectroscopy. We resolve all these features using a Heisenberg-Kondo lattice model for EuB$_6$, solved using exact diagonalisation based Langevin dynamics. Over a temperature window $\sim 0.7T_c - 1.5T_c$ we observe electronic and magnetic textures with the correct spatial and energy scale, and confirm an associated non-monotonic resistivity. We predict a distinctly `non Drude' optical conductivity in the polaronic phase, and propose a field-temperature phase diagram testable through spin resolved tunneling spectroscopy. We argue that the anomalous properties of EuB$_6$, and magnetic polaron materials in general, occur due to a non monotonic change in spatial character of `near Fermi level' eigenstates with temperature, and the appearance of a weak pseudogap near $T_c$. |
| title | Tunneling maps, non-monotonic resistivity, and non Drude optics in EuB$_6$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2408.03628 |