title: Hybrid organic-inorganic conductor with a magnetic chain anion: kappa-BETS2[Fe(III)(C2O4)Cl2] [BETS = bis(ethylenedithio)tetraselenafulvalene].
abstract: The synthesis, crystal structure, and electrical, optical, and magnetic properties of kappa-BETS2[Fe(III)(C2O4)Cl2], where BETS is bis(ethylenedithio)tetraselenafulvalene, are reported. The black plate crystals consist of parallel donor layers, two per unit cell, displaying a kappa-type packing of BETS(0.5+) within the bc plane and anionic magnetic chains, [Fe(C2O4)Cl2-]n, running along the c axis. It displays metallic behavior down to 4.2 K, and analysis of the optical reflectivity data gives unscreened plasma energies of 0.69 eV (E parallel c) and 0.40 eV (E perpendicular c). The optical anisotropy is larger than that seen for other kappa phases and is described well by transfer integrals obtained from extended Hückel calculations. However, the transfer integrals need to be scaled down uniformly by a factor of 1.21 to reproduce the absolute experimental plasma frequencies. The band structure consists of a one-dimensional (1D) band and a hole pocket, characteristics of kappa phases. The magnetic properties were modeled by the sum of a 1D antiferromagnetic chain contribution from the d spins of Fe3+, a temperature-independent paramagnetic contribution, and a Curie impurity term. At 4.5 K, there is a signature of long-range magnetic ordering to a canted-antiferromagnetic state in the zero-field-cooled-field-cooled magnetizations, and at 2 K, a small hysteresis loop is observed.
authors.affiliation: Organic Solid Laboratory, CMS, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China. zhangbin@iccas.ac.cn
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Zheming
authors.initials: Z
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Okano
authors.forename: Hengbo
authors.initials: H
authors.lastname: Cui
authors.forename: Hayao
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Katsuya
authors.initials: K
authors.lastname: Inoue
authors.forename: Mohamedally
authors.initials: M
authors.lastname: Kurmoo
authors.forename: Francis L
authors.initials: FL
authors.lastname: Pratt
authors.forename: Daoben
authors.initials: D
authors.lastname: Zhu