Magnetic behavior of Fe-doped of multicomponent bismuth niobate pyrochlore

Two series of iron-containing solid solutions Bi2Mg1− x Fe x Nb2O9+δ and Bi2MgNb2−2 x Fe2 x O9−δ of pyrochlore structure were obtained by the traditional solid phase synthesis method. The electronic state and character of exchange interactions of iron atoms in solid solutions were investigated by methods of magnetic dilution and NEXAFS-spectroscopy. According to X-ray spectroscopy and magnetic susceptibility data, iron(III) atoms are distributed mainly in octahedral positions of niobium(V) and in a dominant amount are in the charge state of Fe(III) in the form of monomers and exchange-bonded clusters mainly with antiferromagnetic type of exchange. Differences in magnetic behavior of iron-containing solid solutions of both series have been revealed. Antiferromagnetic and ferromagnetic exchange can be realized between iron atoms, which, with increasing concentration of paramagnetic atoms and averaging structure distortions, becomes less significant. The parameters of exchange interactions in clusters and distribution of iron paramagnetic atoms depending on the concentration of solid solutions have been calculated.

A new trap loading mechanism for hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at University of Windsor, Windsor, Ontario, Canada on 21–26 July 2008.

In this paper, we report on our recent advances on a new trap loading mechanism for neutral atoms. The idea is based on our recently published results for chromium spectroscopy of atoms released from a solid neon matrix at cryogenic temperatures. The proposed trap loading mechanism consists of magnetically capturing the low-energy fraction of paramagnetic atoms being released from the matrix, while the host Ne atoms stick to the walls. Two different designs are described: one with a superconducting magnet producing a trap depth of 3 T and another with a superconducting dynamically switched magnet that generates a trap depth of about 1 T. Some preliminary results are presented.