title: Gapless spin liquid of an organic triangular compound evidenced by thermodynamic measurements.
abstract: In frustrated magnetic systems, long-range ordering is forbidden and degeneracy of energy states persists, even at extremely low temperatures. Under certain conditions, these systems form an exotic quantum spin-liquid ground state, in which strongly correlated spins fluctuate in the spin lattices. Here we investigate the thermodynamic properties of an anion radical spin liquid of EtMe(3)Sb[Pd(dmit)(2)](2), where dmit represents 1,3-dithiole-2-thione-4,5-dithiolate. This compound is an organic dimer-based Mott insulator with a two-dimensional triangular lattice structure. We present distinct evidence for the formation of a gapless spin liquid by examining the T-linear heat capacity coefficient, γ , in the low-temperature heat capacity. Using comparative analyses with κ-(BEDT-TTF)(2)Cu(2)(CN)(3), a generalized picture of the new spin liquid in dimer-based organic systems is discussed. We also report anomalous enhancement of γ, produced by a kind of criticality inherent to the Pd(dmit)(2) phase diagram.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Yamashita
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakazawa
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tamura
authors.forename: Reizo
authors.initials: R
authors.lastname: Kato
mesh_terms: D019281:Dimerization; D008280:Magnetics; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013816:Thermodynamics; D014050:Toluene / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: C504559:1,3-dithiole-2-thione-4,5-dithiolate; C472948:BEDT-TTF; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D014050:Toluene