17 research outputs found
Anomalous Hall Effect and Magnetoresistance of SrFe1-xCoxO3-d
Transport and magnetic studies on polycrystalline samples of SrFe1-xCoxO3-d
have been carried out to investigate the relationship between the magnetic
structure and the anomalous Hall resistivity rH. The hysteretic behavior of the
magnetization observed in the measurements with varying temperature T up and
then down after zero field cooling indicates that the system has the reentrant
spin-glass phase, which is supported by the increasing width of the magnetic
reflections observed by neutron diffraction with decreasing T below the Curie
temperature TC. Detailed analyses of the observed Hall resistivity rH indicate
that the anomalous Hall coefficient exhibits unusual behavior in the reentrant
spin-glass phase. The magnetic field (H)- and T-dependence of the
magnetoresistance of the present system can be understood by a spin dependent
tunneling model.Comment: 10 pages, 11 figures, J. Phys. Soc. Jpn. 72 (2003) No.
beta-amino acids to piperidinones by petasis methylenation and acid-induced cyclization
[GRAPHICS] Ester-imine derivatives of beta-amino acids were methylenated with dimethyltitanocene under microwave irradiation and the resulting enol ethers cyclized with Bronsted acid or triisopropylaluminium to give 2,6-syn-disubstituted piperidinones in good yield and diastereoselectivity. The method is analogous to the Petasis-Ferrier rearrangement of 1,3dioxan-4-ones to give tetrahydropyranones