Magnetic Susceptibility Study of Hole-Doped Organic Metal κ-(ET)₄Hg_3-δCl_8,δ=22% and κ-(ET)₄Hg_3-δBr_8,δ=11%

Abstract

The Non-Fermi-Liquid (NFL) state has been one of central issues in the strongly correlated electrons systems. This deviates from conventional Fermi Liquid (FL) behavior. In the hole-doped triangular lattice organic metal κ-(ET)4Hg3-δBr8, δ = 11% (κ-HgBr), the NFL state is observed as a linear temperature dependence of the resistivity which changed to the temperature square dependence behavior by pressure. The spin susceptibility dependence of the muon Knight shift, K(c), is not linear in the region below 50 K, unlike in other k-type organic superconductors. Furthermore, 13C-NMR study under pressure concluded that strong antiferromagnetic spin fluctuations (AFSF) contribute to the origin of NFL. To understand the underlying correlation of the enhanced AFSF and NFL state in k-HgBr, the K(c) plot study in the sister compound κ-(ET)4Hg3-δCl8, δ=22% (κ-HgCl) which shows metal to insulator transition at TMI ~ 20 K is desirable. In this study, we report a precise susceptibility measurement in both k-HgBr and k-HgCl. Furthermore, we summarize the c(T) data of k-HgBr and k-HgCl and discuss them from the viewpoint of the triangular and square lattice models.