Emergent soft-gap Anderson models at quantum criticality in a lattice Hamiltonian within dynamical mean field theory
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arXiv
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| Main Authors: | , , , |
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| Format: | Preprint |
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2022
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| _version_ | 1866914976848936960 |
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| author | K., Sujan K. Kulkarni, Vinayak M. Vidhyadhiraja, N. S. Sen, Sudeshna |
| author_facet | K., Sujan K. Kulkarni, Vinayak M. Vidhyadhiraja, N. S. Sen, Sudeshna |
| contents | Local quantum criticality in itinerant fermion systems has been extensively investigated through the soft-gap Anderson impurity model, wherein a localized, correlated impurity, hybridizes with a broad conduction band with a singular, $|ω|^r$, density of states. However, lattice models hosting quantum critical points (QCPs), do not appear to have such a spectrum emerging at the QCP. In this work, we report the emergence of such a singular form of the density of states in a three-orbital lattice model, within dynamical mean field theory, precisely at a quantum critical point, separating a gapless, Fermi liquid, metallic phase from a gapped, Mott insulating phase. A temperature-dependent exponent, $α$, defined using the corresponding Matsubara self-energy, is found to vary from $+1$ deep in the FL regime, to $-1$ in the Mott insulator regime. Interestingly, we find that $α$ becomes temperature independent, and hence isosbestic, precisely at the QCP. The isosbestic exponent is shown to lead to an emergent soft-gap spectrum, $|ω|^r$ at the QCP, where $r = |α_{\rm iso}|$. We discuss the implications of our findings for non-Fermi liquid behaviour in the quantum critical region of the phase diagram. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2203_07348 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Emergent soft-gap Anderson models at quantum criticality in a lattice Hamiltonian within dynamical mean field theory K., Sujan K. Kulkarni, Vinayak M. Vidhyadhiraja, N. S. Sen, Sudeshna Strongly Correlated Electrons Local quantum criticality in itinerant fermion systems has been extensively investigated through the soft-gap Anderson impurity model, wherein a localized, correlated impurity, hybridizes with a broad conduction band with a singular, $|ω|^r$, density of states. However, lattice models hosting quantum critical points (QCPs), do not appear to have such a spectrum emerging at the QCP. In this work, we report the emergence of such a singular form of the density of states in a three-orbital lattice model, within dynamical mean field theory, precisely at a quantum critical point, separating a gapless, Fermi liquid, metallic phase from a gapped, Mott insulating phase. A temperature-dependent exponent, $α$, defined using the corresponding Matsubara self-energy, is found to vary from $+1$ deep in the FL regime, to $-1$ in the Mott insulator regime. Interestingly, we find that $α$ becomes temperature independent, and hence isosbestic, precisely at the QCP. The isosbestic exponent is shown to lead to an emergent soft-gap spectrum, $|ω|^r$ at the QCP, where $r = |α_{\rm iso}|$. We discuss the implications of our findings for non-Fermi liquid behaviour in the quantum critical region of the phase diagram. |
| title | Emergent soft-gap Anderson models at quantum criticality in a lattice Hamiltonian within dynamical mean field theory |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2203.07348 |