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Magnetic moment

About: Magnetic moment is a(n) research topic. Over the lifetime, 31748 publication(s) have been published within this topic receiving 584480 citation(s). The topic is also known as: magnetic dipole moment & magnetic area moment. more


Journal ArticleDOI: 10.1103/PHYSREV.124.41
Philip W. Anderson1Institutions (1)
01 Oct 1961-Physical Review
Abstract: The conditions necessary in metals for the presence or absence of localized moments on solute ions containing inner shell electrons are analyzed. A self-consistent Hartree-Fock treatment shows that there is a sharp transition between the magnetic state and the nonmagnetic state, depending on the density of states of free electrons, the $s\ensuremath{-}d$ admixture matrix elements, and the Coulomb correlation integral in the $d$ shell; that in the magnetic state the $d$ polarization can be reduced rather severely to nonintegral values, without appreciable free electron polarization because of a compensation effect; and that in the nonmagnetic state the virtual localized $d$ level tends to lie near the Fermi surface. It is emphasized that the condition for the magnetic state depends on the Coulomb (i.e., exchange self-energy) integral, and that the usual type of exchange alone is not large enough in $d$-shell ions to allow magnetic moments to be present. We show that the susceptibility and specific heat due to the inner shell electrons show strongly contrasting behavior even in the nonmagnetic state. A calculation including degenerate $d$ orbitals and $d\ensuremath{-}d$ exchange shows that the orbital angular momentum can be quenched, even when localized spin moments exist, and even on an isolated magnetic atom, by kinetic energy effects. more

Topics: Magnetic moment (57%), Fermi surface (53%), Spin (physics) (52%) more

3,881 Citations

Journal ArticleDOI: 10.1063/1.1729860
Abstract: The valence‐bond theory for the contact electron‐spin coupling of nuclear magnetic moments is used to calculate the proton‐proton, proton‐fluorine, and fluorine‐fluorine coupling constants in ethanic and ethylenic molecules. A considerable simplification is introduced into the theory by approximations which reduce the problem to one involving only a small number of electrons and canonical structures. The agreement between calculated and experimental values is such as to demonstrate that the mechanism considered is the one of primary importance for the nuclear coupling in the compounds studied. Of particular interest is the theoretical confirmation of the observation that in ethylenic compounds the trans coupling between nuclei (HH, HF, FF) is considerably larger than cis coupling. more

Topics: Coupling constant (57%), Coupling (53%), Magnetic moment (51%)

2,697 Citations

Open accessJournal ArticleDOI: 10.1103/PHYSREVB.83.205101
30 Jun 2010-Physical Review B
Abstract: In 5d transition metal oxides such as the iridates, novel properties arise from the interplay of electron correlations and spin-orbit interactions. We investigate the electronic structure of the pyrochlore iridates, (such as Y$_{2}$Ir$_{2}$O$_{7}$) using density functional theory, LDA+U method, and effective low energy models. A remarkably rich phase diagram emerges on tuning the correlation strength U. The Ir magnetic moment are always found to be non-collinearly ordered. However, the ground state changes from a magnetic metal at weak U, to a Mott insulator at large U. Most interestingly, the intermediate U regime is found to be a Dirac semi-metal, with vanishing density of states at the Fermi energy. It also exhibits topological properties - manifested by special surface states in the form of Fermi arcs, that connect the bulk Dirac points. This Dirac phase, a three dimensional analog of graphene, is proposed as the ground state of Y$_{2}$Ir$_{2}$O$_{7}$ and related compounds. A narrow window of magnetic `axion' insulator, with axion parameter $\theta=\pi$, may also be present at intermediate U. An applied magnetic field induces ferromagnetic order and a metallic ground state. more

Topics: Mott insulator (56%), Dirac (software) (54%), Weyl semimetal (53%) more

2,573 Citations

Journal ArticleDOI: 10.1103/PHYSREV.96.99
M. A. Ruderman1, C. Kittel1Institutions (1)
01 Oct 1954-Physical Review
Abstract: A calculation is given of the indirect exchange ${\mathrm{I}}_{i}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{I}}_{j}$ type coupling of nuclear magnetic moments in a metal by means of the hyperfine interaction with the conduction electrons. The interaction appears to account qualitatively for the broad nuclear spin resonance lines observed in natural metallic silver. It is expected that the interaction may sharpen the resonances in pure isotopic specimens. The line shape of the minority isotope in a binary mixture may tend to be Gaussian, while that of the majority isotope may tend to be Lorentzian, if the indirect exchange interaction is dominant. more

Topics: Coupling (probability) (69%), Type (model theory) (64%), RKKY interaction (57%) more

2,469 Citations

Journal ArticleDOI: 10.1126/SCIENCE.1056186
Yuji Matsumoto1, Makoto Murakami1, T. Shono1, Tetsuya Hasegawa1  +6 moreInstitutions (1)
02 Feb 2001-Science
Abstract: Dilute magnetic semiconductors and wide gap oxide semiconductors are appealing materials for magnetooptical devices. From a combinatorial screening approach looking at the solid solubility of transition metals in titanium dioxides and of their magnetic properties, we report on the observation of transparent ferromagnetism in cobalt-doped anatase thin films with the concentration of cobalt between 0 and 8%. Magnetic microscopy images reveal a magnetic domain structure in the films, indicating the existence of ferromagnetic long-range ordering. The materials remain ferromagnetic above room temperature with a magnetic moment of 0.32 Bohr magnetons per cobalt atom. The film is conductive and exhibits a positive magnetoresistance of 60% at 2 kelvin. more

Topics: Magnetic semiconductor (63%), Magnetic domain (61%), Ferromagnetism (58%) more

2,238 Citations

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Topic's top 5 most impactful authors

A. Szytuła

128 papers, 1.1K citations

F.R. de Boer

74 papers, 3K citations

Olle Eriksson

68 papers, 1.6K citations

Olivier Isnard

62 papers, 719 citations

Andrei Rogalev

61 papers, 1.4K citations

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