Electronic correlations and spin frustration in the molecular conductors $κ$-(BEDT-TTF)$_2$X probed by magnetic quantum oscillations

Fuente: arXiv
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Autores principales: Erkenov, Shamil, Fust, Sergej, Oberbauer, Sebastian, Biberacher, Werner, Kushch, Natalia D., Mueller, Harald, Pratt, Francis L., Gross, Rudolf, Kartsovnik, Mark V.
Formato: Preprint
Publicado: 2024
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author Erkenov, Shamil
Fust, Sergej
Oberbauer, Sebastian
Biberacher, Werner
Kushch, Natalia D.
Mueller, Harald
Pratt, Francis L.
Gross, Rudolf
Kartsovnik, Mark V.
author_facet Erkenov, Shamil
Fust, Sergej
Oberbauer, Sebastian
Biberacher, Werner
Kushch, Natalia D.
Mueller, Harald
Pratt, Francis L.
Gross, Rudolf
Kartsovnik, Mark V.
contents The layered molecular conductors $κ$-(BEDT-TTF)$_2$X are a perfect experimental platform for studying the physics of the Mott transition and related exotic electronic states. In these materials, the subtle balance between various instabilities of the normal metallic state can be efficiently changed by applying a very moderate external pressure or by subtle chemical modifications, e.g. by a replacement of the insulating anion X$^{-}$, frequently referred to as ``chemical pressure''. A crucially important but still unsettled issue is an exact understanding of the influence of physical and chemical pressure on the electronic structure. Here, we use magnetic quantum oscillations to explore in a broad pressure range the behavior of the key parameters governing the Mott physics, the electronic correlation strength ratio $U/t$ and the spin frustration ratio $t'/t$ in two $κ$ salts, the ambient-pressure antiferromagnetic insulator with X = Cu[N(CN)$_2$]Cl and the ambient-pressure superconductor with X = Cu(NCS)$_2$. Our analysis shows that pressure effectively changes not only the conduction bandwidth but also the degree of spin frustration, thus weakening both the electronic correlation strength and the magnetic ordering instability. At the same time, we find that the replacement of the anion Cu[N(CN)$_2$]Cl$^-$ by Cu(NCS)$_2^-$ results in a significant increase of the frustration parameter $t'/t$, leaving the correlation strength essentially unchanged.
format Preprint
id arxiv_https___arxiv_org_abs_2409_02799
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Electronic correlations and spin frustration in the molecular conductors $κ$-(BEDT-TTF)$_2$X probed by magnetic quantum oscillations
Erkenov, Shamil
Fust, Sergej
Oberbauer, Sebastian
Biberacher, Werner
Kushch, Natalia D.
Mueller, Harald
Pratt, Francis L.
Gross, Rudolf
Kartsovnik, Mark V.
Strongly Correlated Electrons
The layered molecular conductors $κ$-(BEDT-TTF)$_2$X are a perfect experimental platform for studying the physics of the Mott transition and related exotic electronic states. In these materials, the subtle balance between various instabilities of the normal metallic state can be efficiently changed by applying a very moderate external pressure or by subtle chemical modifications, e.g. by a replacement of the insulating anion X$^{-}$, frequently referred to as ``chemical pressure''. A crucially important but still unsettled issue is an exact understanding of the influence of physical and chemical pressure on the electronic structure. Here, we use magnetic quantum oscillations to explore in a broad pressure range the behavior of the key parameters governing the Mott physics, the electronic correlation strength ratio $U/t$ and the spin frustration ratio $t'/t$ in two $κ$ salts, the ambient-pressure antiferromagnetic insulator with X = Cu[N(CN)$_2$]Cl and the ambient-pressure superconductor with X = Cu(NCS)$_2$. Our analysis shows that pressure effectively changes not only the conduction bandwidth but also the degree of spin frustration, thus weakening both the electronic correlation strength and the magnetic ordering instability. At the same time, we find that the replacement of the anion Cu[N(CN)$_2$]Cl$^-$ by Cu(NCS)$_2^-$ results in a significant increase of the frustration parameter $t'/t$, leaving the correlation strength essentially unchanged.
title Electronic correlations and spin frustration in the molecular conductors $κ$-(BEDT-TTF)$_2$X probed by magnetic quantum oscillations
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2409.02799