Raman studies of BEDT-TTF molecule-based organic superconductors

Y. Lin; J. E. Eldridge; J. Schlueter; H. H. Wang; A. M. Kini

doi:10.1103/PhysRevB.64.024506

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Raman studies of BEDT-TTF molecule-based organic superconductors

Y. Lin, J. E. Eldridge, J. Schlueter, H. H. Wang, A. M. Kini

DOI 10.1103/PhysRevB.64.024506 · Physical Review B

T1

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Abstract

The temperature dependence of the frequencies of the Raman features due to ν9 (Ag) and ν60 (B3g) modes has been measured in the BEDT-TTF (ET) molecule-based organic superconductors κ−(ET)2Cu[N(CN)2]Br, κ−(ET)2Cu[N(CN)2]Cl, αt−(ET)2I3, and β−(ET)2AuI2. The frequency of the ν9 (Ag) mode was observed to soften in κ−(ET)2Cu[N(CN)2]Br and κ−(ET)2Cu[N(CN)2]Cl at low temperatures where NMR data indicated antiferromagnetic fluctuations, providing evidence of spin-phonon interactions. The result is also compared with a very recent theory which deals with the effect of electronic correlations on the frequencies of the molecular phonon modes. We observed a peak splitting for the ν60 (B3g) mode in αt−(ET)2I3 below 190 K, where an incommensurate superstructure was reported, and a frequency decrease of 1.7±0.4 cm−1 for the upper component of the ν60 (B3g) mode in the superconducting compound, demonstrating further the unusual properties of this mode.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
κ-(ET)2Cu[N(CN)2]Br Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	11.6	Pressure not reported	unknown
κ-(ET)2Cu[N(CN)2]Cl Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	12.8	0.03 GPa	unknown
αt-(ET)2I3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	8	Pressure not reported	unknown
β-(ET)2AuI2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.8	Pressure not reported	unknown
κ-(ET)2Cu(NCS)2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10.4	Pressure not reported	unknown
β-(ET)2I3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.3	Pressure not reported	unknown