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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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Journal ArticleDOI
TL;DR: The light rare-earth dicarbides, TbC2 and HoC2, exhibit an antiferromagnetic, elliptic-helical spin alignment propagating along the a axis with the repetition quadrupole of the atomic spacing, where the Neel temperatures are 66° and 26°K, and the root-mean-square ordered moments are 5.1 and 6.9 Bohr magnetons, respectively.
Abstract: The light rare‐earth dicarbides, CeC2, PrC2, and NdC2, having the tetragonal CaC2‐type structure, have been shown by neutron diffraction to become a body‐centered first‐kind antiferromagnet with the Neel temperatures of 33°, 15°, and 29°K and with the ordered moments being 81%, 44%, and 90% of the free‐ion values, respectively. The moment direction is parallel to the c axis in the above compounds. The isostructural heavy rare‐earth dicarbides, TbC2 and HoC2, exhibit an antiferromagnetic, elliptic‐helical spin alignment propagating along the a axis with the repetition quadrupole of the atomic spacing, where the Neel temperatures are 66° and 26°K, and the root‐mean‐square ordered moments are 5.1 and 6.9 Bohr magnetons, respectively. Here, the moments lie on the bc plane. A modulation of the above structure takes place below 40° and 16°K, with the maximum possible additional moments of 0.54 and 1.65 Bohr magnetons at 2°K in TbC2 and HoC2, respectively. In TbC2, another complex magnetic structure coexists below ∼33°K. Also presented are a discussion on the wavy diffuse backgrounds of TbC2 and HoC2 at temperatures down to 2°K, and the low‐temperature crystallographic parameters.

50 citations

Journal ArticleDOI
TL;DR: In this paper, a terahertz spectroscopic study of magnetic excitations in ferroelectric antiferromagnet BiFeO3 is presented, where the authors interpret the observed spectrum of longwavelength magnetic resonance modes in terms of the normal modes of the material's cycloidal Antiferromagnetic structure and find that the modulated Dzyaloshinski-Moriya interaction leads to a splitting of the out-ofplane resonance modes.
Abstract: We present a terahertz spectroscopic study of magnetic excitations in ferroelectric antiferromagnet BiFeO3 We interpret the observed spectrum of long-wavelength magnetic resonance modes in terms of the normal modes of the material's cycloidal antiferromagnetic structure We find that the modulated Dzyaloshinski-Moriya interaction leads to a splitting of the out-of-plane resonance modes We also assign one of the observed absorption lines to an electromagnon excitation that results from the magnetoelectric coupling between the ferroelectric polarization and the cycloidal magnetic structure of BiFeO3

50 citations

Journal ArticleDOI
Akimasa Sakuma1
TL;DR: The first principle calculations for FeMn and MnPt alloys both of ordered and disordered phases have been performed with the TB-LMTO method combined with the CPA as discussed by the authors.
Abstract: The first-principles calculations for FeMn and MnPt alloys both of ordered and disordered phases have been performed with the TB-LMTO method combined with the CPA. The magnetic structure of FeMn in...

50 citations

Journal ArticleDOI
TL;DR: In this article, a simple model for the formation of stable non-propagating structures in a magnetized collisionless plasma is presented, which is based on the following hypothesis: (1) one dimensionality and spatial periodicity, (2) cold electrons, (3) bi-Maxwellian protons as initial condition, (4), conservation of magnetic moment for all protons, (5) conservation of energy for magnetically non trapped particles, (6) spatial pressure balance, (7) evolved structure has a crenellated shape, and (8)
Abstract: A simple model for the formation of stable nonpropagating structures in a magnetized collisionless plasma is presented. The model describes the evolution of an electron-proton plasma from an initially spatially uniform, but unstable, configuration toward a final nonuniform and nonpropagating stable configuration. The model is based on the following hypothesis: (1) one-dimensionality and spatial periodicity, (2) cold electrons, (3) bi-Maxwellian protons as initial condition, (4) conservation of magnetic moment for all protons, (5) conservation of energy for magnetically non trapped protons, (6) spatial pressure balance, (7) evolved structure has a crenellated shape, (8) slow growth of the structure. Given these assumptions all the macroscopic properties of the plasma (density, pressure, and magnetic field) in the saturated state can be computed explicitly. The model shows that a spatially uniform and homogeneous plasma that is unstable against the linear mirror mode can form stable non propagating structures. Thus one can consider the model as a model for the nonlinear mirror instability where the magnetic trapping of protons in the low magnetic field region is the important saturation mechanism. A simple expression for the magnetic field saturation amplitude is found. The pressure balance, between high and low magnetic field regions, which is needed for the evolved structure to be a stable one, is obtained solely through betatron cooling of the trapped protons. Modification of the trapped protons energy due to the Fermi effect seems to be of secondary importance. The model predicts that the evolved structures are characterized by narrow and deep magnetic wells except in the case of very low magnetic pressure (ratio of thermal to magnetic pressure β ≳ 10) where the opposite situation becomes possible. This enforces the idea according to which the proton mirror instability is the driving mechanism for the formation of magnetic holes in high β(≳ 1) plasmas.

50 citations

Journal ArticleDOI
TL;DR: In this article, detailed neutron scattering measurements of the magnetic excitation spectrum of CuCrO$ in the ordered state below 24.2$ K are presented, and the spectra are analyzed using a model Hamiltonian which includes intralayer exchange up to the next-next-nearest neighbor and interlayer exchange.
Abstract: In this paper detailed neutron scattering measurements of the magnetic excitation spectrum of CuCrO${}_{2}$ in the ordered state below ${T}_{\mathrm{N}1}=24.2$ K are presented. The spectra are analyzed using a model Hamiltonian which includes intralayer exchange up to the next-next-nearest neighbor and interlayer exchange. We obtain a definite parameter set and show that exchange interaction terms beyond the next-nearest neighbor are important to describe the inelastic excitation spectrum. The magnetic ground state structure generated with our parameter set is in agreement with the structure proposed for CuCrO${}_{2}$ from the results of single crystal diffraction experiments previously published. We argue that the role of the interlayer exchange is crucial to understand the incommensurability of the magnetic structure as well as the spin-charge coupling mechanism.

50 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202353
202296
2021187
2020224
2019247
2018229