title: Electronic control of spin alignment in pi-conjugated molecular magnets.
abstract: Intramolecular spin alignment in pi-conjugated molecules is studied theoretically in a model of a Peierls-Hubbard chain coupled with two localized spins. By means of the exact diagonalization technique, we demonstrate that a spin singlet (S=0) to quartet (S=3/2) transition can be induced by electronic doping, depending on the chain length, the positions of the localized spins, and the sign of the electron-spin coupling. The calculated results provide a theoretical basis for understanding the mechanism of spin alignment recently observed in a diradical donor molecule.
authors.affiliation: Nanotechnology Research Institute (NRI) and Research Consortium for Synthetic Nano-Function Materials Project (SYNAF), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: Ping
authors.initials: P
authors.lastname: Huai
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Shimoi
authors.forename: Shuji
authors.initials: S
authors.lastname: Abe