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| Main Authors: | , , , , , , |
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| Format: | Preprint |
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2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2601.09420 |
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| _version_ | 1866918288971268096 |
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| author | Chen, A. Kugler, F. B. Doležal, P. Saito, Y. Kawamoto, A. Georges, A. Pustogow, A. |
| author_facet | Chen, A. Kugler, F. B. Doležal, P. Saito, Y. Kawamoto, A. Georges, A. Pustogow, A. |
| contents | Non-Fermi-liquid charge transport in the vicinity of electronic instabilities has been intensely studied for decades. Deviations from $ρ_{\rm FL}=ρ_0+AT^2$ in bad and strange metals are commonly ascribed to a breakdown of Landau's quasiparticle (QP) concept. Yet, it remains unclear what mechanism drives the temperature dependence of $ρ(T)$ beyond $ρ_{\rm FL}$. Here, we examine the bad metal upon approaching the Mott metal-insulator transition via chemical pressure in $κ$-[(BEDT-STF)$_x$(BEDT-TTF)$_{1-x}$]$\rm _2 Cu_2 (CN)_3$. Through nuclear magnetic resonance (NMR) and transport experiments on the same single crystals, we directly link the onset of deviations from Korringa law $(T_1T)^{-1} = \mathrm{const.}$ with the rise of $ρ(T)$ beyond $ρ_{\rm FL}$. From the NMR relaxation rate, we can identify the gradual crossover between the QP-dominated regime at low $T$ to predominant local moments at higher $T$. By comparing our experimental findings with dynamical mean-field theory calculations, which accurately reproduce the transport data, we reveal how this crossover is reflected in $T$-dependent changes of the QP spectrum. Near the Mott insulator, where $dρ/dT<0$ at high $T$, an Einstein-relation analysis shows that bad-metal behavior with $dρ/dT>0$ is driven by the temperature dependence of the electronic compressibility rather than the diffusion constant. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_09420 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Quasiparticle to local moment crossover in bad metals Chen, A. Kugler, F. B. Doležal, P. Saito, Y. Kawamoto, A. Georges, A. Pustogow, A. Strongly Correlated Electrons Non-Fermi-liquid charge transport in the vicinity of electronic instabilities has been intensely studied for decades. Deviations from $ρ_{\rm FL}=ρ_0+AT^2$ in bad and strange metals are commonly ascribed to a breakdown of Landau's quasiparticle (QP) concept. Yet, it remains unclear what mechanism drives the temperature dependence of $ρ(T)$ beyond $ρ_{\rm FL}$. Here, we examine the bad metal upon approaching the Mott metal-insulator transition via chemical pressure in $κ$-[(BEDT-STF)$_x$(BEDT-TTF)$_{1-x}$]$\rm _2 Cu_2 (CN)_3$. Through nuclear magnetic resonance (NMR) and transport experiments on the same single crystals, we directly link the onset of deviations from Korringa law $(T_1T)^{-1} = \mathrm{const.}$ with the rise of $ρ(T)$ beyond $ρ_{\rm FL}$. From the NMR relaxation rate, we can identify the gradual crossover between the QP-dominated regime at low $T$ to predominant local moments at higher $T$. By comparing our experimental findings with dynamical mean-field theory calculations, which accurately reproduce the transport data, we reveal how this crossover is reflected in $T$-dependent changes of the QP spectrum. Near the Mott insulator, where $dρ/dT<0$ at high $T$, an Einstein-relation analysis shows that bad-metal behavior with $dρ/dT>0$ is driven by the temperature dependence of the electronic compressibility rather than the diffusion constant. |
| title | Quasiparticle to local moment crossover in bad metals |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2601.09420 |