Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4}
We present results of the coefficient of thermal expansion for the frustrated quasi-two-dimensional molecular conductor θ-(BEDT-TTF)_{2}RbZn(SCN)_{4} for temperatures 1.5≤T≤290 K. A pronounced first-order phase transition anomaly is observed at the combined charge-order/structural transition at 215 ...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2024-04-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.6.023003 |
| _version_ | 1797210238035689472 |
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| author | Yohei Saito Owen Ganter Chao Shang Kenichiro Hashimoto Takahiko Sasaki Stephen M. Winter Jens Müller Michael Lang |
| author_facet | Yohei Saito Owen Ganter Chao Shang Kenichiro Hashimoto Takahiko Sasaki Stephen M. Winter Jens Müller Michael Lang |
| author_sort | Yohei Saito |
| collection | DOAJ |
| description | We present results of the coefficient of thermal expansion for the frustrated quasi-two-dimensional molecular conductor θ-(BEDT-TTF)_{2}RbZn(SCN)_{4} for temperatures 1.5≤T≤290 K. A pronounced first-order phase transition anomaly is observed at the combined charge-order/structural transition at 215 K. Furthermore, clear evidence is found for two separate glasslike transitions at T_{g}=90–100 K and T_{g}^{†}=120–130 K, similar to previous findings for θ-(BEDT-TTF)_{2}CsZn(SCN)_{4} and θ-(BEDT-TTF)_{2}CsCo(SCN)_{4} reported by Thomas et al. [Phys. Rev. B 105, L041114 (2022)2469-995010.1103/PhysRevB.105.L041114], both of which lack the charge-order/structural transition. Our findings indicate that these glasslike transitions are common features for the θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} family, with M=(Rb, Cs) and M^{′}=(Co, Zn), irrespective of the presence or absence of charge order. These results are consistent with our model calculations on the glasslike dynamics associated with the flexible ethylene end groups of the BEDT-TTF molecules for various θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} salts, predicting two different conformational glass transitions. Moreover, calculations of the hopping integrals show a substantial degree of dependence on the end groups' conformation, suggesting a significant coupling to the electronic degrees of freedom. Our findings support the possibility that the glassy freezing of the ethylene end groups could drive or enhance glassy charge dynamics. |
| first_indexed | 2024-04-24T10:07:25Z |
| format | Article |
| id | doaj.art-74dddfff2bb54394b88069d0882c609e |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:07:25Z |
| publishDate | 2024-04-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-74dddfff2bb54394b88069d0882c609e2024-04-12T17:41:03ZengAmerican Physical SocietyPhysical Review Research2643-15642024-04-016202300310.1103/PhysRevResearch.6.023003Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4}Yohei SaitoOwen GanterChao ShangKenichiro HashimotoTakahiko SasakiStephen M. WinterJens MüllerMichael LangWe present results of the coefficient of thermal expansion for the frustrated quasi-two-dimensional molecular conductor θ-(BEDT-TTF)_{2}RbZn(SCN)_{4} for temperatures 1.5≤T≤290 K. A pronounced first-order phase transition anomaly is observed at the combined charge-order/structural transition at 215 K. Furthermore, clear evidence is found for two separate glasslike transitions at T_{g}=90–100 K and T_{g}^{†}=120–130 K, similar to previous findings for θ-(BEDT-TTF)_{2}CsZn(SCN)_{4} and θ-(BEDT-TTF)_{2}CsCo(SCN)_{4} reported by Thomas et al. [Phys. Rev. B 105, L041114 (2022)2469-995010.1103/PhysRevB.105.L041114], both of which lack the charge-order/structural transition. Our findings indicate that these glasslike transitions are common features for the θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} family, with M=(Rb, Cs) and M^{′}=(Co, Zn), irrespective of the presence or absence of charge order. These results are consistent with our model calculations on the glasslike dynamics associated with the flexible ethylene end groups of the BEDT-TTF molecules for various θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} salts, predicting two different conformational glass transitions. Moreover, calculations of the hopping integrals show a substantial degree of dependence on the end groups' conformation, suggesting a significant coupling to the electronic degrees of freedom. Our findings support the possibility that the glassy freezing of the ethylene end groups could drive or enhance glassy charge dynamics.http://doi.org/10.1103/PhysRevResearch.6.023003 |
| spellingShingle | Yohei Saito Owen Ganter Chao Shang Kenichiro Hashimoto Takahiko Sasaki Stephen M. Winter Jens Müller Michael Lang Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} Physical Review Research |
| title | Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} |
| title_full | Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} |
| title_fullStr | Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} |
| title_full_unstemmed | Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} |
| title_short | Combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ-(BEDT-TTF)_{2}MM^{′}(SCN)_{4} |
| title_sort | combined experimental and theoretical studies on glasslike transitions in the frustrated molecular conductors θ bedt ttf 2 mm scn 4 |
| url | http://doi.org/10.1103/PhysRevResearch.6.023003 |
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