| 1. |
- Bengone, Oliver, et al.
(författare)
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Origin of the negative giant magnetoresistance effect in Co1-xCrx/Cu/Co (111) trilayers
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:9, s. 092406-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study on Co1-xCrx/Cu/Co (111) trilayers, where a transition from positive to negative giant magnetoresistance effect has been observed experimentally, with increasing thickness of the alloyed layer. The theory, based on a recently implemented conductance calculation, reproduces quantitatively this observation, and the effect is found to be caused by alloying effects, due to a virtual bound Cr d state in the majority spin channel of the Co-Cr layer.
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| 2. |
- Castleton, C W M, et al.
(författare)
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Ab initio study of neutral vacancies in InP using supercells and finite size scaling
- 2003
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 340, s. 407-411
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Tidskriftsartikel (refereegranskat)abstract
- The formation energies and relaxed structures of the neutral vacancies in InP are calculated by planewave density functional theory, using supercells of 8, 64, 216 and 512 atoms together with finite size scaling. The effects of electrostatic defect-defect interactions and the truncation of elastic relaxations by the finite supercell are examined. The unrelaxed formation energies are 4.95+/-0.10 and 3.00+/-0.10eV for V-In(+0) and V-P(+0) respectively, and the relaxed formation energies are 4.20+/-0.05 and 2.35+/-0.15 eV. When relaxed, V-In(+0) remains very nearly symmetric with a 40% volume reduction, V-P(+0) on the other hand develops a double dimerized structure, with an similar to12% Jahn-Teller distortion and a 45% volume reduction. It is shown that finite size scaling sometimes reveals that energies are not converged even in the 512 atom supercell, and can thus be important tool in theoretical studies of defects in semiconductors, if sufficient care is taken with strongly Jahn Teller active defects.
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| 3. |
- Castleton, C W M, et al.
(författare)
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Finite-size scaling as a cure for supercell approximation errors in calculations of neutral native defects in InP
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:19, s. 195202-
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Tidskriftsartikel (refereegranskat)abstract
- The relaxed and unrelaxed formation energies of neutral antisites and interstitial defects in InP are calculated using ab initio density functional theory and simple cubic supercells of up to 512 atoms. The finite-size errors in the formation energies of all the neutral defects arising from the supercell approximation are examined and corrected for using finite-size scaling methods, which are shown to be a very promising approach to the problem. Elastic errors scale linearly, while the errors arising from charge multipole interactions between the defect and its images in the periodic boundary conditions have a linear plus a higher order term, for which a cubic provides the best fit. These latter errors are shown to be significant even for neutral defects. Instances are also presented where even the 512 atom supercell is not sufficiently converged. Instead, physically relevant results can be obtained only by finite-size scaling the results of calculations in several supercells, up to and including the 512 atom cell and in extreme cases possibly even including the 1000 atom supercell.
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| 4. |
- Duda, LC, et al.
(författare)
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Soft-x-ray emission study of Fe/V(001) superlattices
- 1996
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. - 0163-1829. ; 54:15, s. 10393-10396
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have studied the electronic structure of the interfaces in bet Fe/V (001) superlattices (SL's) grown on MgO(001) with soft-x-ray emission spectroscopy. Two samples with different thicknesses of Fe and V were investigated: [(V)(2)/(Fe)(5)](60) and [(V)(
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| 5. |
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| 6. |
- Mikkelsen, Anders, et al.
(författare)
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Defect structure of Ga1-xMnxAs: A cross-sectional scanning tunneling microscopy study
- 2004
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 70:8
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the atomic scale structure of molecular beam epitaxy grown Ga1-xMnxAs compounds with various Mn concentrations by cross-sectional scanning tunneling microscopy and first principles calculations. Only bright protrusions close to the top layer As atoms are directly correlated with the bulk Mn concentration. Atomically resolved filled and empty states images of this defect are compared to images derived from first principles calculations. We identify the Mn related defect as substitutional Mn in the second layer Ga site. Surprisingly no substitutional Mn is observed in the top-most Ga layer. The experimental results are consistent with the energetics of our first principles total energy calculations.
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| 7. |
- MIRBT, S, et al.
(författare)
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CALCULATED OSCILLATION PERIODS OF EXCHANGE COUPLING IN FE/MO/FE SANDWICHES
- 1995
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Ingår i: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS. - : ELSEVIER SCIENCE BV. - 0304-8853. ; 148:1-2, s. 191-192
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have performed an ab initio study of the oscillation periods of the exchange coupling in sandwiches of bcc (100) layers of Mo embedded in an Fe host. We find three periods for the exchange coupling, which are in close agreement with the corresponding p
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| 8. |
- Mirbt, S, et al.
(författare)
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Calculated oscillation periods of the interlayer coupling in Fe/Cr/Fe and Fe/Mo/Fe sandwiches
- 1996
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. - 0163-1829. ; 54:9, s. 6382-6392
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have performed an ab initio study of the oscillation periods of the interlayer coupling in sandwiches of [100] layers of body centered cubic Cr, respectively, Mo, with up to 20 monolayers thickness embedded in an Fe host. Our derived values for the osc
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| 9. |
- Mirbt, S, et al.
(författare)
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Magnetic coupling in 3d transition-metal monolayers and bilayers on bcc (100) iron
- 1995
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. ; 52:21
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We have calculated the magnetization profile in the (100) surface of bcc Fe covered by a monolayer or a bilayer of 3d transition metals. The calculated trends are explained in terms of the hybridization between the 3d states of the overlayer and the Fe su
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| 10. |
- Mirbt, S, et al.
(författare)
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Magnetic properties of Fe embedded in V and Cr: Thin films and dilute alloys
- 1997
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Ingår i: PHYSICAL REVIEW B-CONDENSED MATTER. - : AMER INST PHYSICS. - 0163-1829. ; 55:1, s. 67-69
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We have calculated the magnetic moment of Fe as a function of the number of nearest V and Cr atoms. We find that the Fe magnetic moment disappears in a neighborhood of exclusively V atoms, but remains larger than 1.85 mu(B) in a Cr neighborhood. This beha
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