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A. B. Harris - One of the best experts on this subject based on the ideXlab platform.
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theoretical analysis of the double q Magnetic Structure of ceal2
Physical Review B, 2006Co-Authors: A. B. Harris, J SchweizerAbstract:A model involving competing short-range isotropic Heisenberg interactions is developed to explain the "double-q" Magnetic Structure of CeAl$_2$. For suitably chosen interactions, terms in the Landau expansion quadratic in the order parameters explain the condensation of incommensurate order at wavevectors in the star of (1/2 $-\delta$, 1/2 $+\delta$, 1/2)$(2\pi/a)$, where $a$ is the cubic lattice constant. We show that the fourth order terms in the Landau expansion lead to the formation of the so-called "double-q" Magnetic Structure in which long-range order develops simultaneously at two symmetry-related wavevectors, in striking agreement with the Magnetic Structure determinations. Based on the value of the ordering temperature and of the Curie-Weiss $\Theta$ of the susceptibility, we estimate that the nearest neighbor interaction $K_0$ is ferroMagnetic, with $K_0/k=-11\pm 1$K and the next-nearest neighbor interaction $J$ is antiferroMagnetic with $J/k=6 \pm 1$K. We also briefly comment on the analogous phenomenon seen in the similar system TmS.
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Magnetic Structure and spin waves in the kagome jarosite compound kfe 3 so 4 2 oh 6
Physical Review B, 2006Co-Authors: Taner Yildirim, A. B. HarrisAbstract:We present a detailed study of the Magnetic Structure and spin waves in the Fe jarosite compound ${\rm KFe_3(SO_4)_2(OH)_6}$ for the most general Hamiltonian involving one- and two-spin interactions which are allowed by symmetry. We compare the calculated spin-wave spectrum with the recent neutron scattering data of Matan {\it et al.} for various model Hamiltonians which include, in addition to isotropic Heisenberg exchange interactions between nearest ($J_1$) and next-nearest ($J_2$) neighbors, single ion anisotropy and Dzyaloshinskii-Moriya (DM) interactions. We concluded that DM interactions are the dominant anisotropic interaction, which not only fits all the splittings in the spin-wave spectrum but also reproduces the small canting of the spins out of the Kagom\'e plane. A brief discussion of how representation theory restricts the allowed Magnetic Structure is also given.
G P Felcher - One of the best experts on this subject based on the ideXlab platform.
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spin flop transition in a finite antiferroMagnetic superlattice evolution of the Magnetic Structure
Physical Review Letters, 2002Co-Authors: S Te G E Velthuis, J S Jiang, S D Bader, G P FelcherAbstract:An antiferroMagnetic (AF) superlattice of Fe/Cr(211) is used as a model system to study Magnetic transitions in a finite-size geometry. With polarization neutron reflectometry the Magnetic Structure at the surface spin-flop transition and its evolution with field is determined. A domain wall created near the surface penetrates the superlattice with increasing field, splitting it into two antiphase, AF domains. After reaching the center the spin-flopped phase spreads throughout the superlattice. The experimental results are in substantial agreement with theoretical and numerical predictions.
Kindo K. - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Structure and high-field magnetization of the distorted kagome lattice antiferromagnet Cs$_2$Cu$_3$SnF$_{12}$
'American Physical Society (APS)', 2021Co-Authors: Matan K., Ono T., Gitgeatpong G., De Roos K., Miao P., Torii S., Kamiyama T., Miyata A., Matsuo A., Kindo K.Abstract:High-resolution time-of-flight powder neutron diffraction and high-field magnetization were measured to investigate the Magnetic Structure and existence of a field-induced Magnetic phase transition in the distorted kagome antiferromagnet Cs$_2$Cu$_3$SnF$_{12}$. Upon cooling from room temperature, the compound undergoes a structural phase transition at $T_\textrm{t}=185$ K from the rhombohedral space group $R\bar{3}m$ with the perfect kagome spin network to the monoclinic space group $P2_1/n$ with the distorted kagome planes. The distortion results in three inequivalent exchange interactions among the $S=1/2$ Cu$^{2+}$ spins that Magnetically order below $T_\textrm{N}=20.2$ K. Magnetization measured with a Magnetic field applied within the kagome plane reveals small in-plane ferromagnetism resulting from spin canting. On the other hand, the out-of-plane magnetization does not show a clear hysteresis loop of the ferroMagnetic component nor a prominent anomaly up to 170 T, with the exception of the subtle knee-like bend around 90 T, which could indicate the 1/3 magnetization plateau. The combined analysis using the irreducible representations of the Magnetic space groups and Magnetic Structure refinement on the neutron powder diffraction data suggests that the Magnetic moments order in the Magnetic space group $P2_1'/n'$ with the all-in-all-out spin Structure, which by symmetry allows for the in-plane canting, consistent with the in-plane ferromagnetism observed in the magnetization.Comment: 14 pages, 9 figures, published version with typos correcte
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Magnetic Structure and high-field magnetization of the distorted kagome lattice antiferromagnet Cs$_2$Cu$_3$SnF$_{12}$
'American Physical Society (APS)', 2019Co-Authors: Matan K., Ono T., Gitgeatpong G., De Roos K., Miao P., Torii S., Kamiyama T., Miyata A., Matsuo A., Kindo K.Abstract:High-resolution time-of-flight powder neutron diffraction and high-field magnetization were measured to investigate the Magnetic Structure and existence of a field-induced Magnetic phase transition in the distorted kagome antiferromagnet Cs$_2$Cu$_3$SnF$_{12}$. Upon cooling from room temperature, the compound undergoes a structural phase transition at $T_\textrm{t}=185$ K from the rhombohedral space group $R\bar{3}m$ with the perfect kagome spin network to the monoclinic space group $P2_1/n$ with the distorted kagome planes. The distortion results in three inequivalent exchange interactions among the $S=1/2$ Cu$^{2+}$ spins that Magnetically order below $T_\textrm{N}=20.2$ K. Magnetization measured with a Magnetic field applied within the kagome plane reveals small in-plane ferromagnetism resulting from spin canting. On the other hand, the out-of-plane magnetization does not show a clear hysteresis loop of the ferroMagnetic component nor a prominent anomaly up to 170 T, with the exception of the subtle knee-like bend around 90 T, which could indicate the 1/3 magnetization plateau. The combined analysis using the irreducible representations of the Magnetic space groups and Magnetic Structure refinement on the neutron powder diffraction data suggests that the Magnetic moments order in the Magnetic space group $P2_1'/n'$ with the all-in-all-out spin Structure, which by symmetry allows for the in-plane canting, consistent with the in-plane ferromagnetism observed in the magnetization.Comment: 14 pages, 9 figure
F Klose - One of the best experts on this subject based on the ideXlab platform.
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hidden spin order induced room temperature ferroelectricity in a peculiar conical Magnetic Structure
Physical Review B, 2017Co-Authors: Shipeng Shen, Xinzhi Liu, Yisheng Chai, Andrew J Studer, K C Rule, Kun Zhai, Liqin Yan, Dashan Shang, F KloseAbstract:A novel mechanism of spin-induced ferroelectricity is unraveled in the alternating longitudinal conical (ALC) Magnetic Structure. Because the noncollinear ALC Structure possesses a $c$-axis component with collinear \ensuremath{\uparrow}--\ensuremath{\uparrow}--\ensuremath{\downarrow}--\ensuremath{\downarrow} spin order, spin-driven ferroelectricity along the $c$ axis due to the exchange striction mechanism is predicted. Our experiments verify this prediction in the Y-type hexaferrite $\mathrm{B}{\mathrm{a}}_{0.3}\mathrm{S}{\mathrm{r}}_{1.7}\mathrm{C}{\mathrm{o}}_{2}\mathrm{F}{\mathrm{e}}_{11}\mathrm{Al}{\mathrm{O}}_{22}$, where ferroelectricity along the $c$ axis is observed up to room temperature. Neutron diffraction data clearly reveal the ALC phase and its evolution with Magnetic fields. The $c$-axis electric polarization can be well modulated by applying either $ab$-plane or $c$-axis Magnetic fields, even at 305 K. This kind of spin-induced ferroelectricity associated with the ALC Magnetic Structure provides a new resource of type II multiferroics.
S Satpathy - One of the best experts on this subject based on the ideXlab platform.
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electronic and Magnetic Structure of the lamno3 2n srmno3 n superlattices
Physical Review B, 2009Co-Authors: B R K Nanda, S SatpathyAbstract:We study the Magnetic Structure of the ${({\text{LaMnO}}_{3})}_{2n}/{({\text{SrMnO}}_{3})}_{n}$ superlattices from density-functional calculations. In agreement with the experiments, we find that the magnetism changes with the layer thickness $n$. The reason for the different Magnetic Structures is shown to be the varying potential barrier across the interface, which controls the leakage of the $\text{Mn-}{e}_{g}$ electrons from the ${\text{LaMnO}}_{3}$ side to the ${\text{SrMnO}}_{3}$ side. This in turn affects the interfacial magnetism via the carrier-mediated Zener double exchange. For the $n=1$ superlattice, the $\text{Mn-}{e}_{g}$ electrons are more or less spread over the entire lattice so that the Magnetic behavior is similar to the equivalent alloy compound ${\text{La}}_{2/3}{\text{Sr}}_{1/3}{\text{MnO}}_{3}$. For larger $n$, the ${e}_{g}$ electron transfer occurs mostly between the two layers adjacent to the interface, thus leaving the magnetism unchanged and bulklike away from the interface region.
