Charge-induced spin polarization in non-magnetic organic molecule Alq3_{3}

Electrical injection in organic semiconductors is a key prerequisite for the realization of organic spintronics. Using density-functional theory calculations we report the effect of electron transfer into the organic molecule Alq$_3$. Our first-principles simulations show that electron injection spontaneously spin-polarizes non-magnetic Alq$_3$ with a magnetic moment linearly increasing with induced charge. An asymmetry of the Al--N bond lengths leads to an asymmetric distribution of injected charge over the molecule. The spin-polarization arises from a filling of dominantly the nitrogen $p_z$ orbitals in the molecule's LUMO together with ferromagnetic coupling of the spins on the quinoline rings.Comment: Accepted 4 pages 4 figure

Anomalous Ferromagnetism of Monatomic Co Wire at the Pt(111) Surface Step Edge

A first-principles investigation of the anomalous ferromagnetism of a quasi-one-dimensional Co chain at the Pt(111) step edge is reported. Our calculations show that the symmetry breaking at the step leads to an easy magnetization axis at an odd angle of $\sim20^{\circ}$ {\em towards} the Pt step, in agreement with experiment [P. Gambardella {\em et al.}, {\em Nature} {\bf 416}, 301 (2002)]. Also, the Co spin and orbital moments become noncollinear, even in the case of a collinear ferromagnetic spin arrangement. A significant enhancement of the Co orbital magnetic moment is achieved when modest electron correlations are treated within LSDA+$U$ calculations.Comment: Presented at MRS Meeting in Boston, Dec. 2003; 4 pages including 3 figure