Direct evidence of dimensionality enhancement of Q1D TMTSF and DMET salts

Magnetoresistance measurement was carried out for quasi-one-dimensional (Q1 D) organic superconductors, (TMTSF)(2)PF6, (DMET)(2)AuI2 and (DMET)(2)I-3 a t 1.2 K up to about 15 kbar. The third angular effect (TAE) is observed in their metallic state as an hump anomaly of the angular dependence of the ma gnetoresistance. It has been found that the angular width of the TAE hump a nomaly increases with increasing hydrostatic pressure. This is the first di rect evidence of the dimensionality enhancement by pressure for the Q1D sup erconductors, where the dimensionality is defined as the anisotropy of the transfer integrals, t(y)/t(x).