| 1. |
- Eriksson, Therese, et al.
(författare)
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Crystal and magnetic structure of Mn3IrSi
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:5, s. 054422-
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Tidskriftsartikel (refereegranskat)abstract
- A new ternary Ir-Mn-Si phase with stoichiometry Mn3IrSi has been synthesized and found to crystallize in the cubic AlAu4-type structure, space group P213 with Z=4, which is an ordered form of the β-Mn structure. The unit cell dimension was determined by x-ray powder diffraction to a=6.4973(3)Å. In addition to the crystal structure, we have determined the magnetic structure and properties using superconducting quantum interference device magnetometry and Rietveld refinements of neutron powder diffraction data. A complex noncollinear magnetic structure is found, with magnetic moments of 2.97(4)μB at 10 K only on the Mn atoms. The crystal structure consists of a triangular network built up by Mn atoms, on which the moments are rotated 120° around the triangle axes. The magnetic unit cell is the same as the crystallographic and carries no net magnetic moment. The Néel temperature was determined to be 210 K. A first-principles study, based on density functional theory in a general noncollinear formulation, reproduces the experimental results with good agreement. The observed magnetic structure is argued to be the result of frustration of antiferromagnetic couplings by the triangular geometry.
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| 2. |
- Eriksson, Therese, et al.
(författare)
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Crystal structure and magnetic properties of the new phase Mn3IrSi
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; :272-276, s. 823-825
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Tidskriftsartikel (refereegranskat)abstract
- A new phase in the ternary Ir–Mn–Si system has been synthesised. From powder neutron diffraction data the crystal structure was determined to be of the AlAu4 type and to be described in the cubic space group P213 with the unit cell a=6.4973(3) Å. Susceptibility measurements using a SQUID-magnetometer showed a transition typical of antiferromagnetism, with TN=210 K. Low temperature antiferromagnetic order is confirmed by extra peaks in neutron diffractograms recorded at 10 and 80 K.
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| 3. |
- Eriksson, Therese, et al.
(författare)
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Cycloidal magnetic order in the compound IrMnSi
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 71:17
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Tidskriftsartikel (refereegranskat)abstract
- A new compound, IrMnSi, has been synthesized, and its crystal structure and magnetic properties have been investigated by means of neutron powder diffraction, magnetization measurements, and first-principles theory. The crystal structure is found to be of the TiNiSi type (ordered Co2P, space groupPnma). The Mn-projected electronic states are situated at the Fermi level, giving rise to metallic binding, whereas a certain degree of covalent character is observed for the chemical bond between the Ir and Si atoms. A cycloidal, i.e., noncollinear, magnetic structure was observed below 460 K, with the propagation vector q=[0,0,0.4530(5)] at 10 K. The magnetism is dominated by large moments on the Mn sites, 3.8μB∕atom from neutron diffraction. First-principles theory reproduces the propagation vector of the experimental magnetic structure as well as the angles between the Mn moments. The calculations further result in a magnetic moment of 3.2μB for the Mn atoms, whereas the Ir and Si moments are negligible, in agreement with observations. A calculation that more directly incorporates electron-electron interactions improves the agreement between the theoretical and experimental magnetic moments. A band mechanism is suggested to explain the observed magnetic order.
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| 4. |
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| 5. |
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| 6. |
- Eriksson, Therese, et al.
(författare)
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Structural and magnetic characterization of Mn3IrGe and Mn3Ir(Si1-xGex) : experiments and theory
- 2004
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 177:11, s. 4058-4066
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Tidskriftsartikel (refereegranskat)abstract
- The Structural and magnetic propertiesof a new ternary Ir-Mn-Ge phase, Mn3IrGe, as well as the solid solution Mn3Ir(Si1_xGex), O ordering is found below a critical temperature of about 225 K. The magnetic structure is noncollinear, as a result of frustrated magnetic interactions on a triangular network of Mn atoms, on which the moments rotate 120° around the triangle axes. The magnitude of the magnetic moment at 10 K is 3.39(4) µB for Mn3IrGe. The theoretical calculations reproduce with very good accuracy the magnitudes as well as the directions of the experimentally observed magnetic moments.
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| 7. |
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| 8. |
- Andersson, Gabriella, et al.
(författare)
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Perpendicular magnetocrystalline anisotropy in tetragonally distorted Fe-Co alloys
- 2006
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 96:3
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Tidskriftsartikel (refereegranskat)abstract
- We report on the experimental realization of tetragonal Fe-Co alloys as a constituent of Fe(0.36)Co(0.64)/Pt superlattices with huge perpendicular magnetocrystalline anisotropy energy, reaching 210 mu eV/atom, and a saturation magnetization of 2.5 mu(B)/atom at 40 K, in qualitative agreement with theoretical predictions. At room temperature the corresponding values 150 mu eV/atom and 2.2 mu(B)/atom are achieved. This suggests that Fe-Co alloys with carefully chosen combinations of composition and distortion are good candidates for high-density perpendicular storage materials.
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| 9. |
- Cedervall, Johan, et al.
(författare)
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Low temperature magneto-structural transitions in Mn3Ni20P6
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Academic Press Inc.. - 0022-4596 .- 1095-726X. ; 237, s. 343-348
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Tidskriftsartikel (refereegranskat)abstract
- X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm3¯m (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 12) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.
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| 10. |
- Choudhury, Debraj, et al.
(författare)
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Tuning of dielectric properties and magnetism of SrTiO3 by site-specific doping of Mn
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 84:12, s. 125124-
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Tidskriftsartikel (refereegranskat)abstract
- Combining experiments with first-principles calculations, we show that site-specific doping of Mn into SrTiO(3) has a decisive influence on the dielectric properties of these doped systems. We find that phonon contributions to the dielectric constant invariably decrease sharply on doping at any site. However, a sizable, random dipolar contribution only for Mn at the Sr site arises from a strong off-centric displacement of Mn in spite of Mn being in a non-d(0) state; this leads to a large dielectric constant at higher temperatures and gives rise to a relaxor ferroelectric behavior at lower temperatures. We also investigate magnetic properties in detail and critically reevaluate the possibility of a true multiglass state in such systems.
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