Chalcogenides ferromagnetic

In europium metal and in a number of cubic chalcogenide compounds the europium ion is divalent, and NMR has been used to investigate the ordered state (see section 5.2)l Measurements have also been made on a number of trivalent ions in ordered insulating compounds. The precision obtainable is illustrated by Ho in the ferromagnet Ho(OH)3, where the spectrum is centred on 5013(1) MHz, and a pseudo-octupolar term w/j with w = 0.25 MHz is needed (see section 5.4) to fit the... 

For the lanthanide chalcogenides, it was demonstrated experimentally that Sm, Eu, and Yb are divalent in their sulphide, selenide, and telluride compounds, while Tm becomes divalent for the telluride phase only (Jayaraman, 1978, 1979). The SIC-LSD calculations find all the Eu chalcogenides, including EuO, to be insulators in the ferromagnetic state, and to have a divalent configuration... 

It is quite natural that not all authors and not all papers could be included in this review due to the limited amount of space and capability of the author. But since this article is not the only review and probably not the last one on this topic the problems and materials will always be illuminated from different points of view. With respect to magnetic semiconductors we want to recall that non-rare earth compounds like the Cr spinels (Haas, 1970) offer similar effects as the Eu chalcogenides. Also the group of the RE-pnictides may become ferromagnetic semiconductors with increasing purity and perfection of the samples, but at the moment their conduction mechanism is still in discussion (see also F. Hulliger, vol. 4, ch. 33 of this Handbook). 

As is well known, the U chalcogenides are all ferromagnets we will discuss them more extensively in connection with inelastic neutron experiments, see the chapter by Holland-Moritz and Lander in vol. 19. For Np the situation is clear only for NpS and NpSe. NpS was studied many years ago in polycrystalline form (Lam et al. 1974), and recent single crystal work (Blaise et al. 1992) has confirmed that the structure is of type II with k =, ) and the Fourier components, / , directed along either... 

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