01668nas a2200265 4500008004100000022001300041245010200054210006900156300001400225490000700239520088100246100001301127700001101140700001401151700001801165700002101183700001101204700001501215700002301230700001501253700002401268700001901292700001401311856007701325 2000 eng d a1098012100aElectrical transport and magnetic properties of a possible electron-doped layered manganese oxide0 aElectrical transport and magnetic properties of a possible elect a4141-41450 v613 aWe report on the structural, transport, and magnetic properties of (Formula presented) thin films grown in vacuum by pulsed-laser deposition. The as-grown thin films have both the matrix (Formula presented) phase with (Formula presented) structure and an embedded MnO phase. The electrical transport and magnetic properties of the films are determined mainly by those of the matrix phase. By annealing, the as-grown thin films can be transformed into the normal (Formula presented) single phase, which shows the expected colossal magnetoresistance effect. Based on the composition of the matrix phase, and the structural, electrical, and magnetic properties of the films, we propose that the matrix phase is possibly electron doped with a mixed valence of (Formula presented) instead of the (Formula presented) as in the hole-doped case. © 2000 The American Physical Society.1 aZhao, Y.1 aLi, Y.1 aOgale, S.1 aRajeswari, M.1 aSmolyaninova, V.1 aWu, T.1 aBiswas, A.1 aSalamanca-Riba, L.1 aGreene, R.1 aRamesh, Ramamoorthy1 aVenkatesan, T.1 aScott, J. uhttps://rameshlab.lbl.gov/publications/electrical-transport-and-magnetic01726nas a2200193 4500008004100000022001300041245007400054210006900128300001400197490000700211520113400218100001401352700001401366700001501380700001501395700002401410700001901434856007901453 1998 eng d a1098012100aMagnetotransport anisotropy effects in epitaxial magnetite thin films0 aMagnetotransport anisotropy effects in epitaxial magnetite thin a7823-78280 v573 aEpitaxial films of magnetite (Formula presented) have been grown on (Formula presented) (100) and sapphire (α-(Formula presented) 0001) substrates by pulsed laser deposition, and they exhibit crystal orientations of [100] and [111], respectively. Films of both orientations show a clear Verwey transition near 120 K. The temperature dependence of magnetoresistance of the films is examined at fields up to 8.5 T applied parallel to the film plane. The [100] oriented films show a pronounced extremum in magnetoresistance (MR) at the Verwey transition temperature (Formula presented) while no such feature is observed in the case of the [111] oriented films. However, the [111] oriented films exhibit a sudden change in the MR dependence on (Formula presented) at (Formula presented) and films of both orientations show a rapid increase of MR as the temperature is decreased below about 110 K. An attempt is made to analyze these data in terms of the known anisotropy in magnetostriction and optical magnon-phonon dispersions, and the small polaron band and hopping conductivity mechanisms. © 1998 The American Physical Society.1 aOgale, S.1 aGhosh, K.1 aSharma, R.1 aGreene, R.1 aRamesh, Ramamoorthy1 aVenkatesan, T. uhttps://rameshlab.lbl.gov/publications/magnetotransport-anisotropy-effects01436nas a2200193 4500008004100000022001300041245012100054210006900175300001600244490000700260520080100267100001501068700001401083700001301097700002401110700001501134700001901149856007401168 1996 eng d a1098012100aDirect evidence for the effect of lattice distortions in the transport properties of perovskite-type manganite films0 aDirect evidence for the effect of lattice distortions in the tra a10014-100180 v543 aWe report ion channeling investigations in crystalline colossal magnetoresistance films of (Formula presented)(Formula presented)(Formula presented), (Formula presented)(Formula presented)(Formula presented), and (Formula presented)(Formula presented)(Formula presented). The measured full width at half maximum of the channeling angular scans exhibit a dramatic increase with decreasing temperature which is larger than expected from a simple Debye model. The temperature range where such a change is observed overlaps with the peak magnetoresistance regions in the three cases. The observed effect is an order of magnitude larger than previously found by volumetric measurements and seems to provide a direct evidence for a dynamic Jahn-Teller distortion. © 1996 The American Physical Society.1 aSharma, R.1 aXiong, G.1 aKwon, C.1 aRamesh, Ramamoorthy1 aGreene, R.1 aVenkatesan, T. uhttps://rameshlab.lbl.gov/publications/direct-evidence-effect-lattice