Topic
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 paper, the magnetic structure of uranium dioxide has been investigated using linear augmented plane wave ab initio calculations, taking into account spin-orbit coupling, strong Coulomb correlation (using the $\mathrm{LDA}+U$ approach) and noncollinear magnetism.
Abstract: The magnetic structure of uranium dioxide has been investigated using linear augmented plane wave ab initio calculations, taking into account spin-orbit coupling, strong Coulomb correlation (using the $\mathrm{LDA}+U$ approach) and noncollinear magnetism. The collinear 1-k antiferromagnetic type-I structure and the noncollinear antiferromagnetic 2-k and 3-k orderings have been tested. The 1-k and 2-k structures can be excluded by a comparison between the calculated and experimental uranium electric field gradients (EFG). It is shown that the measured EFG agrees with theory only in the 3-k structure and an additional deformation of the oxygen cage with an oxygen displacement of ${\ensuremath{\Delta}}_{O}=0.16\mathrm{a}.\mathrm{u}.$ Also the magnetic moments and the corresponding hyperfine fields agree reasonably well with experiment.
138 citations
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TL;DR: In this paper, the voltage control of a spin-filter magnetoresistance (TMR) formed by four-layer chromium triiodide (CrI3) sandwiched by monolayer graphene contacts in a dual-gated structure was investigated.
Abstract: Atomically thin chromium triiodide (CrI3) has recently been identified as a layered antiferromagnetic insulator, in which adjacent ferromagnetic monolayers are antiferromagnetically coupled. This unusual magnetic structure naturally comprises a series of antialigned spin filters, which can be utilized to make spin-filter magnetic tunnel junctions with very large tunneling magnetoresistance (TMR). Here we report voltage control of TMR formed by four-layer CrI3 sandwiched by monolayer graphene contacts in a dual-gated structure. By varying the gate voltages at fixed magnetic field, the device can be switched reversibly between bistable magnetic states with the same net magnetization but drastically different resistance (by a factor of 10 or more). In addition, without switching the state, the TMR can be continuously modulated between 17,000% and 57,000%, due to the combination of spin-dependent tunnel barrier with changing carrier distributions in the graphene contacts. Our work demonstrates new kinds of ma...
138 citations
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TL;DR: In this article, the authors show that the susceptibility is remarkably field dependent in the temperature range near TN for some samples with larger lithium contents, which might be understood in terms of field-induced short-range ferromagnetic correlations.
Abstract: λ-MnO2, a metastable form of manganese dioxide, retains the cubic spinel structure upon lithium removal from LiMn2O4 by soft chemical methods, either electrochemical or acid leaching. The minimum lithium content, achieved by the latter route at pH 1, is Li0.10MnO2, which is in reasonable agreement with previous reports. For lithium contents near the minimum value, long-range antiferromagnetic order sets in below TN = 32 K, and Curie−Weiss susceptibility behavior is found above 125 K, with fitting constants, θc = −104(4) K and C = 1.97(2) emu-K/mol. This value of C is consistent with the lithium content found analytically. The susceptibility is remarkably field dependent in the temperature range near TN for some samples with larger lithium contents, which might be understood in terms of field-induced short-range ferromagnetic correlations. Neutron diffraction studies show a complex magnetic order described by a propagation vector k = (1/21/21/2)(128 Mn moments per magnetic unit cell) and confirm the TN = 3...
138 citations
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137 citations
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TL;DR: Polarized-neutron specular reflectometry (PNR) was developed in the 1980s as a means of measuring depth-resolved magnetization in flat films with characteristic thicknesses from 2 to 5000 A as mentioned in this paper.
137 citations