Dimensionality of superconductivity in the layered organic material EtMe3P[Pd(dmit)2]2 under pressure

We measured the ac magnetic susceptibility for the layered organic superconductor ${\mathrm{EtMe}}_{3}\mathrm{P}{[\mathrm{Pd}{(\mathrm{dmit})}_{2}]}_{2}$ under pressure with a dc magnetic field applied perpendicular to the ac field. We investigated the dc field dependence of the ac susceptibility in detail and concluded that the superconductivity in ${\mathrm{EtMe}}_{3}\mathrm{P}{[\mathrm{Pd}{(\mathrm{dmit})}_{2}]}_{2}$ is an anisotropic three-dimensional superconductivity even at low temperatures, which contrasts with the large majority of other correlated electron layered superconductors such as high-${T}_{\mathrm{c}}$ cuprate and $\ensuremath{\kappa}$-(${\mathrm{ET})}_{2}X$ systems.