Search results

Sort By:

Limit search:

Resonance Raman Investigations of Low Energetic Modes in the Organic Superconductors α_{t}-(BEDT-TTF)_{2}I_{3} and β-(BEDT-TTF)_{2}IAuI

100%

Ludwig T., Schweitzer D., Keller H. J.

Acta Physica Polonica A

1995

vol. 87

issue 4-5

801-806

A study of low energetic modes in the resonance Raman spectra of the organic superconductors α_{t}-(BEDT-TTF)_{2}I_{3} (T_{c} = 8 K) and β-(BEDT-TTF)_{2}IAuI (T_{c} = 4 K) in the temperature range of 1.5-100 K was performed. In both materials, a strong vanishing of low energetic phonon bands (at 30 cm^{-1} and 40 cm^{-1} for α_{t}-(BEDT-TTF)_{2}I_{3} and at 27 cm^{-1} and 33 cm^{-1} for β-(BEDT-TTF)_{2}IAuI) below 71 was observed. For the symmetric stretching mode of the I¯_{3} and the IAuI¯ anion at 120 cm^{-1} no change below T, was found. In addition, wavelength dependent measurements on α-(BEDT-TTF)_{2}I_{3} were performed, indicating that the modes around 30 cm^{-1} are probably librational modes of the BEDT-TTF molecules.

Investigations of Fermi Surfaces and Effective Masses of the Organic Superconductors (BEDO-TTF)_{2}ReO_{4}(H_{2}O) and κ-(BEDT-TTF)_{2}I_{3} by Shubnikov-de Haas and de Haas-van Alphen Measurements

64%

Schweitzer D., Balthes E., Karlich S., Heinen I., Keller H. J., Strunz W., Biberacher W., Jansen A. G. M., Steep E.

Acta Physica Polonica A

1995

vol. 87

issue 4-5

749-759

The Fermi surfaces and effective masses of (BEDO-TTF)_{2}ReO_{4}(H_{2}0) and κ-(BEDT-TTF)_{2}I_{3} were investigated by Shubnikov–de Haas (SdH) and de Haas–van Alphen (dHvA) measurements in magnetic fields up to 27 T in the temperature range from 0.5 K to 4.2 K. Two small closed pockets (0.7% and 1.5% of the first Brillouin zone) are observed in (BEDO-TTF)_{2}ReO_{4}(H_{2}0) corresponding very well with two cross-sectional areas of the Fermi surfaces obtained for a hole and an electron pocket from tight binding calculations. In contrast, in κ-(BEDT-TTF)_{2}I_{3} two relatively large closed sections (13% and 85% of the first Brillouin zone) of the Fermi surfaces are observed, again confirming the tight binding calculations. For κ-(BEDT-TTF)_{2}I_{3} in magnetic fields above 12 T the effective mass for the larger orbit, as obtained from the temperature dependence of the SdH-oscillation amplitudes, is magnetic field dependent as long as the field is arranged perpendicular to the conducting planes (Θ = 0°). In contrast, from dHvA measurements - which were performed by turning the magnetic field by 27° with respect to the SdH experiments - the observed effective mass is field independent. We suppose that the occurrence of anyons at temperatures below 1 K and in fields above 12 T might be the reason for the observed field dependence of the effective mass in the SdH investigations under the special angle 0°.

Refine search results

2 Acta Physica Polonica A

2 1995

2 Keller H. J.

2 Schweitzer D.

1 Balthes E.

1 Biberacher W.

1 Heinen I.

1 Jansen A. G. M.

1 Karlich S.

1 Ludwig T.

1 Steep E.

1 Strunz W.

Search results

Resonance Raman Investigations of Low Energetic Modes in the Organic Superconductors α_{t}-(BEDT-TTF)_{2}I_{3} and β-(BEDT-TTF)_{2}IAuI

Investigations of Fermi Surfaces and Effective Masses of the Organic Superconductors (BEDO-TTF)_{2}ReO_{4}(H_{2}O) and κ-(BEDT-TTF)_{2}I_{3} by Shubnikov-de Haas and de Haas-van Alphen Measurements