High-field magnetic resonant properties of β’–(ET)2SF5CF2SO3

The charge transfer salt {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3}, which has previously been considered a spin-Peierls material with a T{sub SP}-33K, is examined using high-resolution high-field sub-millimeter/millimeter wave electron spin resonance (ESR), and nuclear magnetic resonance (NMR) techniques. A peak in the nuclear spin-lattice relaxation behavior in fields of 8 T, accompanied by a broadening and paramagnetic shift of the resonance line, indicates a phase transition at T{sub c}-20K. A pronounced change in the high-field ESR excitation spectra at -24T, observed at T{sub c}-20K, may indicate the onset of antiferromagnetic (AFM) correlations of the low temperature phase in {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3}. Pecularities of the low-temperature magnetic and resonance properties of {beta}'-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3} are discussed.