arXiv subjects

Hayao Kobayashi

Publications and source records attributed to Hayao Kobayashi.

2 recordsLinked to original sources

arXiv2012

NMR Evidence for Antiferromagnetic Transition in the Single-Component Molecular System, [Cu(tmdt)$_{2}$]

The magnetic state of the single-component molecular compound, [Cu(tmdt)$_{2}$], is investigated by means of $^{1}$H-NMR. An abrupt spectral broadening below 13 K and a sharp peak in nuclear spin-lattice relaxation rate, $T_{1}^{-1}$, at 13 K are observed as clear manifestations of a second-order antiferromagnetic transition, which is consistent with the previously reported magnetic susceptibility and EPR measurement. The ordered moment is estimated at $0.22-0.45$ $μ_{\rm B}$/molecule. The temperature-dependence of $T_{1}^{-1}$ above the transition temperature indicates one-dimensional spin dynamics and supports that the spins are on the central part of the molecule differently from other isostructural compounds.

cond-mat.str-el↗

arXiv2008

Single-Component Molecular Metals as Multiband π-d Systems

Electronic states of single-component molecular metals M(tmdt)2 (M = Ni, Au) are studied theoretically. We construct an effective three-band Hubbard model for each material by numerical fitting to first-principles band calculations, while referring to molecular orbital calculations for the isolated molecules. The model consists of two kinds of base orbital for each molecule with hybridization between them, i.e., a π-character orbital for each of the two tmdt ligands, and, a pdπ-orbital for M = Ni or a pdσ-orbital for M = Au centered on the metal site; this indicates that these materials can be considered as novel multiband π-d systems. We find that both orbitals contribute to realize the metallic character in Ni(tmdt)2. The origin of the antiferromagnetic transition observed in Au(tmdt)2 is also discussed based on this model.

cond-mat.str-el↗