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- Demidov, V. V., et al.
(författare)
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Magnetic anisotropy in strained manganite films and bicrystal junctions
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 113:16
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Tidskriftsartikel (refereegranskat)abstract
- Transport and magnetic properties of La0.67Sr0.33MnO3 (LSMO) manganite thin films and bicrystal junctions were investigated. Epitaxial manganite films were grown on SrTiO3, LaAlO3, NdGaO3 (NGO), and (LaAlO3)(0.3) + (Sr2AlTaO6)(0.7) substrates, and their magnetic anisotropy were determined by two independent techniques of magnetic resonance spectroscopy. It was demonstrated that by using these techniques, a small (0.3%) anisotropy of crystal structure at the (110) surface plane of the orthorhombic NGO substrate leads to uniaxial magnetic anisotropy of the films in the plane of the substrate at least at the room temperature. It was found that on vicinal NGO substrates, the value of magnetic anisotropy strength can be varied in the range 100-200 Oe at T = 295 K by changing the substrate vicinal angle from 0 degrees to 25 degrees. Measurement of the magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetic spin subsystems for both types of bicrystal boundaries with tilting of basal plane of manganite tilted bicrystal (TB-junction) and with rotation of crystallographic axes (RB-junction) used for comparison. The magnetoresistance of TB-junctions increases with decreasing temperature and the misorientation angle. Variation of bicrystal misorientation angle does not lead to change of misorientation of easy magnetic axes in the film parts forming TB-junction. Analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the LSMO bicrystal junctions can be caused by two scattering mechanisms. The first one is the spin-flip of spin-polarized carriers due to the strong electron-electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the second one is spin-flip by antiferromagnetic magnons at high temperatures.
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| 6. |
- Johansson, Sverker
(författare)
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A study of mu-mu- and e-mu-pairs produced in 450 GeV/c p-Be--collisions in HELIOS, and software development for DELPHI.
- 1990
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The main part of this thesis treats measurements in the HELIOS experiment of the production of e-mu and mu+mu-pairs in 450 GeV/c p-Be collisions. The mumu measurement covers the kinematical covers the kinematical range of 2Mmu < M < 1.5 GeV, 0.03 < xF < 0.25, and 0 < pT < 2 GeV. Production of the vector mesons rho, omega , and phi is observed. The branching ratio omega to mu+mu- is for the first time experimentally measured. The continuum at masses below the mu mass is studied, and compared with the contributions from known sources, normalized to the vector meson peaks in the mu+mu- mass spectrum, and to measurements in this experiment of the mu cross section. The res ult is compared with that of other experiments, discussed in terms of different background estimates used. A significant signal of unlike-sign e-mu-pairs is observed, forming a continuum peaking at a mass below 500 MeV. Correlations between e-mu and neutrino production are studied. The shape of the e-mu mass and missng-energy spectra indicate significant non-charm contributions. A search for lepton-number-violating decays is made, resulting in upper limits on a number of branching ratios. Also discussed here is the author's work in the DELPHI experiment, contributions that are related to analysis of heavy quark production. Keywords: muon. pair, dimuon, dilepton, lepton, low mass, continuum, eta, rho, omega, branching ratio, emu, e-mu, mue, mu-e, muon-electron, electron-muon, electron, charm, neutrino, missing energy
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| 8. |
- Johansson, Sverker
(författare)
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Dimuon production in 450 GeV/c p-Be collisions
- 1990
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Ingår i: Proceedings of the Pittsburgh Workshop on Soft Lepton Pair and Photon Production, Sept 6-8, 1990.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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