Magnetic properties of intermediate incommensurate phase in EtMeSb[Pd(dmit)] studied by SR

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

Molecule-based organic conductor EtMeSb[Pd(dmit)] is a two-dimensional triangular lattice system with spin-1/2. The system is suggested to undergo a first order transition to a charge separation (CS) phase with formation of a spin-singlet state at = 70 K. Recently, it was found by a high-resolution X-ray diffraction measurement that an intermediate incommensurate phase, where the degree of spatial distortion of the triangular lattice is modulated, appears below = 105 K and then the commensurate CS phase appears below = 66.5 K. We performed SR measurements on this system to investigate magnetic dynamics in the incommensurate and commensurate phases. A small enhancement of the muon spin relaxation was observed below , in addition to a drastic increase in the muon spin relaxation rate below . Our result may indicate that the magnetic correlation significantly coupled with the lattice structure changes at .