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- Bondarenko, N., et al.
(författare)
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Spin-polaron formation and magnetic state diagram in La-doped CaMnO3
- 2017
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 95:22
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Tidskriftsartikel (refereegranskat)abstract
- LaxCa1-xMnO3 (LCMO) has been studied in the framework of density functional theory (DFT) using Hubbard-U correction. We show that the formation of spin polarons of different configurations is possible in the G-type antiferromagnetic phase. We also show that the spin-polaron (SP) solutions are stabilized due to an interplay of magnetic and lattice effects at lower La concentrations and mostly due to the lattice contribution at larger concentrations. Our results indicate that the development of SPs is unfavorable in the C- and A-type antiferromagnetic phases. The theoretically obtained magnetic state diagram is in good agreement with previously reported experimental results.
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| 6. |
- Eriksson, Martin O., et al.
(författare)
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Recombination processes in Mg doped wurtzite InN films with p- and n-type conductivity
- 2019
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Ingår i: AIP Advances. - : AMER INST PHYSICS. - 2158-3226. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Obtaining high quality, wurtzite InN films with p-type conductivity is a challenge, and there is limited information about the photoluminescence (PL) characteristics of such films. In this study, we present a comprehensive PL study and discuss in detail the recombination processes in Mg-doped InN films with varying Mg concentrations. We find that at low Mg-doping of 1x10(18) cm(-3), which yields p-type conductivity, the PL in InN is spatially inhomogeneous. The latter is suggested to be associated with the presence of n-type pockets, displaying photoluminescence at 0.73 eV involving electrons at the Fermi edge above the conduction band edge. Increasing the Mg concentration to 2.9x10(19) cm(-3) in p-type InN yields strong and spatially uniform photoluminescence at 0.62 eV and 0.68 eV visible all the way to room temperature, indicating homogeneous p-type conductivity. An acceptor binding energy of 64 meV is determined for the Mg acceptor. Further increase of the Mg concentration to 1.8x10(20) cm(-3) leads to switching conductivity back to n-type. The PL spectra in this highly doped sample reveal only the emission related to the Mg acceptor (at 0.61 eV). In the low-energy tail of the emission, the multiple peaks observed at 0.54 - 0.58 eV are suggested to originate from recombination of carriers localized at stacking faults. (C) 2019 Author(s).
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| 7. |
- Eriksson, Therese, et al.
(författare)
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Magnetic properties of selected Mn-based transition metal compounds with β-Mn structure: Experiments and theory
- 2005
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Ingår i: Physical Review B. ; 72:14, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Two compounds, Mn3CoSi and Mn3CoGe have been synthesized and found to crystallize in the AlAu4 type structure, an ordered form of the β-Mn structure. The magnetic structure and properties have been studied by magnetometry and neutron powder diffraction and the theoretical work is based on first principles total energy calculations. Comparison is made with the magnetic properties of the isostructural compounds Mn3IrGe and Mn3IrSi. The solid solutions Mn3Ir1–yCoySi (0y1) and Mn3CoSi1–xGex (0x1) are also studied. A noncollinear antiferromagnetic structure is experimentally observed for y=0.20 as well as for x=0.50 and 1.0, similar to that of Mn3IrSi and Mn3IrGe, with 120° angles between magnetic moments on a triangular network of Mn atoms, and this finding is corroborated by theoretical calculations. For y=0.80–1.0 a transformation to a new type of magnetic structure takes place. The magnetic transition temperature decreases on decreasing unit cell dimension, with good qualitative agreement with the decay of the calculated interatomic exchange energy. Both theory and experiments find the magnitude of the Mn magnetic moment to decrease on decreasing unit cell volume, the same trend is found in calculations for β-Mn.
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| 9. |
- Korzhavyi, Pavel A., 1966-, et al.
(författare)
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Defect-induced magnetic structure in (Ga1-xMnx)As
- 2002
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 88:18, s. 187202-
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Tidskriftsartikel (refereegranskat)abstract
- We show that magnetic structures involving partial disorder of local magnetic moments on the Mn atoms in (Ga1-xMnx)As lower the total energy, compared to the case of perfect ferromagnetic ordering, when As defects on the Ga sublattice are present. Such magnetic structures are found to be stable for a range of concentrations of As antisites, and this result accounts for the observed magnetic moments and critical temperatures in (Ga1-xMnx)As . We propose an explanation for the stabilization of the partially disordered magnetic structures and conclude that the magnetization and critical temperatures should increase substantially by reducing the number of As antisite defects.
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