32 research outputs found
Charge-induced spin polarization in non-magnetic organic molecule Alq
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. Our first-principles simulations show that electron injection
spontaneously spin-polarizes non-magnetic Alq 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
orbitals in the molecule's LUMO together with ferromagnetic coupling of the
spins on the quinoline rings.Comment: Accepted 4 pages 4 figure
Effect of short-range order on the electronic structure and optical properties of the CuZn alloy : an augmented space approach
In this work we have combined the generalized augmented space method
introduced by one of us with the recursion method of Haydock et al (GASR),
within the framework of the local density functional based linear muffin-tin
orbitals basis (TB-LMTO). Using this we have studied the effect of short-range
ordering and clustering on the density of states, optical conductivity and
reflectivity of 50-50 CuZn alloys. Our results are in good agreement with
alternative techniques. We argue that the TB-LMTO-GASR is a feasible, efficient
and quantitatively accurate computational technique for the study of
environmental effects in disordered binary alloys.Comment: 11 pages 11 figure
Antiferromagnetic coupling of Cr-porphyrin to a bare Co substrate
We report the discovery of an antiferromagnetic coupling of the magnetic moment of chromium(II) tetraphenyl-porphyrin (CrTPP) molecules to the magnetization of the clean ferromagnetic Co(001) substrate. We assign this unusual molecule-substrate exchange coupling to the less than half-filled chromium 3d orbitals interacting with Co valence band electrons via porphyrin-ligand molecular orbitals. X-ray magnetic circular dichroism, x-ray photoelectron spectroscopy, and scanning tunneling microscopy are combined with DFT+U calculations and provide evidence for a surprising type of antiferromagnetic 90∘ indirect magnetic exchange coupling