ESR study on π - d correlated molecular salt with benzo group

Abstract

Electron spin resonance (ESR) experiments on (Benzo - TTFVS)2 FeBr4 have been done with 15.4 GHz microwave by using aligned four single crystals, where Benzo-TTFVS denotes a new donor molecule with benzo group, benzotetrathiafulvalenothioquinone-1,3-dithiolemethide. FeBr4 includes Fe(III) d electron spin and an antiferromagnetic ordering occurs below the temperature of TN = 5.8 K. We consider that observed ESR signals originate from d electrons at Fe ions. The shifts in a g-value and the broadening of a line width due to the antiferromagnetic fluctuation are observed at higher temperatures than TN. The g-value and the line width for H | | b are different from those for other directions. The b direction is the direction of the π - d interaction along which donor molecules and counter anions are stacked alternately. These results suggest that the strong fluctuation is related to the π - d correlation. © 2006 Elsevier B.V. All rights reserved.