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Magnetic structure
About: Magnetic structure is a research topic. Over the lifetime, 10787 publications have been published within this topic receiving 207143 citations.
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TL;DR: In this article, the magnetic structure of the cubic gamma-Fe100-xCox (x < 4) alloy precipitates is studied by neutron diffraction, and spin-density wave (SDW) propagating along the cubic axis is found for these specimens.
Abstract: An X-ray diffraction study reveals that an introduction of a small amount of Co suppresses the structural phase transition of gamma -Fe precipitates in Cu and the cubic gamma -FeCo alloy precipitates are available even at the lowest temperature. The magnetic structure of the cubic gamma -Fe100-xCox (x<4) alloy precipitates is studied by neutron diffraction, and spin-density wave (SDW) propagating along the cubic axis is found for these specimens. The Neel temperature and wavelength of the SDW decrease with increasing Co concentration. It is demonstrated that the magnetic structure of the cubic gamma -Fe precipitates is also the SDW state.
153 citations
TL;DR: In this article, the 3d Fe moment on different sites in Y2Fe14B at 4.2 K is closely related to local environment, and it is reduced to 1.95 μB by 4d−3d electron transfer and hybridization for Fe atoms which have the largest coordinance number of Y atoms.
Abstract: Outstanding permanent magnet properties were recently observed in a Nd‐Fe‐B compound which was shown to crystallize in a new phase, R2Fe14B. Polarized neutron measurements are reported on Y2Fe14B and Nd2Fe14B single crystals. The 3d Fe moment on different sites in Y2Fe14B at 4.2 K is closely related to local environment. Its value is maximum for atoms in σ‐like layers at the center of an Fe antiprism. On the contrary, it is reduced to 1.95 μB by 4d‐3d electron transfer and hybridization for Fe atoms which have the largest coordinance number of Y atoms, 4. The measurements at 250 K reveal a larger thermal decrease of the 3d moment for Fe atoms which exhibit shortest Fe‐Fe interatomic distances. This property reveals a reduction of 3d magnetic interactions for short distances as was previously observed in R2Fe17 compounds. In Nd2Fe14B, the low values obtained at 4.2 K for Nd magnetic moments suggest that the magnetic structure, determined by a competition between 3d‐4f exchange interactions and crystal‐fiel...
152 citations
TL;DR: In this paper, a systematic procedure for magnetic structure determination is proposed, which takes into account the restrictions imposed on spin directions by space groups, and is applied to chalcopyrite, which is found to be antiferromagnetic at room temperature: the chemical structure is that proposed by Pauling and Brockway, the space group $I\overline{4}2d$ holds for the magnetic structure, in which the two iron (and possibly also the two copper) atoms tetrahedrally bonded to a common sulfur atom have antiparallel spins directed along
Abstract: The transformation properties of magnetic moments under symmetry and antisymmetry operations lead to 1421 possible space groups for ferromagnetic and antiferromagnetic crystal structures. A systematic procedure for magnetic structure determination is proposed, which takes into account the restrictions imposed on spin directions by space groups. This method is applied to chalcopyrite, CuFe${\mathrm{S}}_{2}$, which is found to be antiferromagnetic at room temperature: the chemical structure is that proposed by Pauling and Brockway, the space group $I\overline{4}2d$ holds for the magnetic structure, in which the two iron (and possibly also the two copper) atoms tetrahedrally bonded to a common sulfur atom have antiparallel spins directed along the $c$ axis. A value of 3.85 \ensuremath{\mu}B is found for the iron moment (0\ifmmode\pm\else\textpm\fi{}0.20 \ensuremath{\mu}B for copper). The possible existence of a second chalcopyrite modification in nature, suggested by conflicting results on material of Japanese origin, is ruled out, as specimens from both Ugo, Japan and Joplin, Missouri are found to have the same structure.
152 citations
TL;DR: In this paper, the magnetic structure of MnBi$_2$Te$_4$ below T$_N$ was determined by powder and single crystal neutron diffraction measurements, which indicated that the magnetic order in Mn-Te layer has negligible effect on the electronic band structure.
Abstract: Millimeter-sized MnBi$_2$Te$_4$ single crystals are grown out of Bi-Te flux and characterized by measuring magnetic and transport properties, scanning tunneling microscope (STM) and spectroscopy (STS). The magnetic structure of MnBi$_2$Te$_4$ below T$_N$ is determined by powder and single crystal neutron diffraction measurements. Below T$_N$=24\,K, Mn$^{2+}$ moments order ferromagnetically in the \textit{ab} plane but antiferromagnetically along the crystallographic \textit{c} axis. The ordered moment is 4.04(13) $\mu_{B}$/Mn at 10\,K and aligned along the crystallographic \textit{c}-axis. The electrical resistivity drops upon cooling across T$_N$ or when going across the metamagnetic transition in increasing fields below T$_N$. A critical scattering effect was observed in the vicinity of T$_N$ in the temperature dependence of thermal conductivity. However, A linear temperature dependence was observed for thermopower in the temperature range 2K-300K without any anomaly around T$_N$. These indicate that the magnetic order in Mn-Te layer has negligible effect on the electronic band structure, which makes possible the realization of proposed topological properties in MnBi$_2$Te$_4$ after fine tuning of the electronic band structure.
151 citations
TL;DR: In this paper, a theoretical analysis of the classical model compared to neutron scattering experiments on the real material, both below and above T-N=1.173(2) K, is presented.
Abstract: Er2Ti2O7 has been suggested to be a realization of the frustrated XY pyrochlore lattice antiferromagnet, for which theory predicts fluctuation-induced symmetry breaking in a highly degenerate ground state manifold. We present a theoretical analysis of the classical model compared to neutron scattering experiments on the real material, both below and above T-N=1.173(2) K. The model correctly predicts the ordered magnetic structure, suggesting that the real system has order stabilized by zero-point quantum fluctuations that can be modeled by classical spin wave theory. However, the model fails to describe the excitations of the system, which show unusual features.
150 citations