superexchange

superexchange

[¦sü·pər·iks′chānj]
(solid-state physics)
A phenomenon in which two electrons from a double negative ion (such as oxygen) in a solid go to different positive ions and couple with their spins, giving rise to a strong antiferromagnetic coupling between the positive ions, which are too far apart to have a direct exchange interaction.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Goodenough is widely credited for the identification and development of the Li-ion rechargeable battery and for developing the Goodenough-Kanamori rules for determining the sign of the magnetic superexchange in materials.
LDA + DMFT calculations [2], for example, showed that the superexchange mechanisms in KCu[F.sub.3] are not strong enough to stabilize the cJTd up to the high temperature regime where it is experimentally still found to survive.
The above results indicated that the Curie temperature of the magnetic phases generally decreased with the increase of Zn content as a consequence of the reduction of the superexchange interaction.
The existing dependence of [H.sub.pp] on the concentration of Zn is due to the superexchange interaction between [Ni.sup.2+] and [Fe.sup.2+] through nonmagnetic [O.sup.2-] ions.
This observation can be analyzed in terms of change in lattice spacing from the secondary rhombohaedral phase and in terms of superexchange interaction.
As can be seen from Table 15; Figure 4, Mn(II) complex of L1 shows subnormal magnetic moment which may be due to metal-metal interactions or due to spin-exchange or superexchange in the solid state [76,77].
The topics of the papers include the Anderson model of magnetic impurities, the study of spin glasses, the fluctuating valence problem and superexchange, the Josephson effect, and the "Higgs" mechanism in elementary particle physics.
Magnetic interactions occur via superexchange. Another set of antiparallel spins are located in the edge-sharing Fe2-Fe3 octahe dral sites.
The ferromagnetic nature decreased for these concentrations which may be ascribed to the fact that some Sm atoms approach each other leading to superexchange interactions between them.
The superexchange between [Mn.sup.3+] neighbors leads to lower [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] levels, whereas the [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] level is rarely affected (see Figure 4(b)).
However, the slight decrease in relaxation time with the addition of EDTA is due to the decrease in electron motion and weakening of superexchange interaction in lattice [34,37].