Pressure effect on the magnetic susceptibility of low dimensional organic conductors ∝, β- (BEDT-TTF)₂I₃ and (TMTSF)₂X (X = ClO₄, PF₆, ReO₄

The pressure dependence of the static susceptibility of the α and β phases of (BEDT-TTF)₂I₃ and of (TMTSF)₂X for X = ClO₄^-, PF₆^-, ReO₄^- was measured using a Faraday balance up to a pressure of 10 kbar. The fractional pressure dependence δ 1nξ_s/δP is -2.0%/kbar and -3.3%/kbar for the α- and β-(BEDT-TTF)₂I₃ respectively and it is temperature independent. For (TMTSF)₂X δ1nξ_s/δP is about -3.0%/kbar at room temperature and increases to -4.8%/kbar on cooling. Both the magnitude and temperature dependence of the fractional pressure dependence in those two families are in contrast with the behaviour in TTF-TCNQ, where the magnitude is -8.%/kbar and decreases with decreasing temperature.