Effects of anion size and disorder on spin resonance in the BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salts
The effect of different linear trihalide anions on electron spin resonance (ESR) spectra have been studied for single crystals of four BEDT-TTF salts plus one crystal containing mixed anions. Structural disorder is reflected in an increased low-temperature (residual) ESR linewidth for both ..beta..-(BEDT-TTF)/sub 2/I/sub 3/ and ..beta..-(BEDT-TTF)/sub 2/I/sub 2/Br and for (nominally) ..beta..-(BEDT-TTF)/sub 2/(AuI/sub 2/)/sub 0.82/(I/sub 3/)/sub 0.18/. Suppression of the disorder transition in ..beta..-(BEDT-TTF)/sub 2/I/sub 3/ by application of shear stress to form the ..beta../sup */-phase decreases the residual linewidth while increasing the onset of superconductivity from 1.5 to approx.8/degree/K. Anion size (or equivalently unit cell size) has been shown to correlate with the superconducting transition temperature in these isomorphic salts, but we find no correlation between anion size and the ESR spin susceptibility, linewidth or microwave conductivity. 22 refs., 4 figs., 1 tab.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA); Argonne National Lab., IL (USA)
- DOE Contract Number:
- AC04-76DP00789; W-31109-ENG-38
- OSTI ID:
- 7144765
- Report Number(s):
- SAND-88-0559C; CONF-880669-8; ON: DE88013022
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANIONS
BEDT-TTF
CHARGED PARTICLES
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON SPIN RESONANCE
GOLD COMPOUNDS
GOLD IODIDES
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
IODIDES
IODINE COMPOUNDS
IONS
LINE WIDTHS
MAGNETIC RESONANCE
MONOCRYSTALS
ORDER-DISORDER TRANSFORMATIONS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RESONANCE
SUPERCONDUCTIVITY
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS