Spin dynamics of intermediate incommensurate phase in EtMeSb[Pd(dmit)] studied by SR

Kawamura, Seiko   ; Guerin, L.*; Watanabe, Isao*; Kato, Reizo*

Anion radical salt [Pd(dmit)] ( is a counter cation) has a two-dimensional isotropic/distorted triangular lattice structure formed by Pd(dmit) dimers. Spin-1/2 is localized at each dimer in an insulating phase. One of them, EtMeSb[Pd(dmit)], has been suggested to exhibit an isotropic triangular lattice structure and to occur a first-order transition to charge separation accompanying with formation of spin-singlet state at = 70 K. We have obtained the evidence for the appearance of the spin-singlet state from previous muon spin relaxation (SR) measurements on this system. However, the temperature at which the muon spin relaxation rate shows an anomaly was slightly different from suggested one. Recently, a high-resolution X-ray structure analysis reported that this system exhibits an incommensurate structure phase below = 105 K and a commensurate charge separation phase below = 66.5 K. We performed additional SR study, and observed a slight increase in dynamical component below and an obvious enhancement of the dynamical fluctuation below .