Laves phase compounds magnetization

Besnus et al. (1982) have performed magnetization, diffuse neutron scattering, 57Fe Mossbauer and NMR studies on these C15 Laves phase compounds over a wide range of composition. The Curie temperatures and average moments are reduced with increasing Mn content and it was concluded from the neutron and NMR data... 

Van Dongen, J.C.M., G.J. Nieuwenhuys, J.A. Mydosh, A.H. van der Kraan and K.H.J. Buschow, 1980, Magnetic Properties and Electrical Resistivity of Transition Metal Laves Phase Compounds Y(Coi iFei)2, Y(Iri, Fe,)2, and HfCCoi-jFexlz, in Rhodes, P., ed.. Physics of Transition Metals, 1980 (Conference Series Nr. 55. The Institute of Physics, Bristol and London) p. 275. 

Cannon et al. (1975) used the Jaccarino-Walker model for the transition-metal moment in some cubic Laves phase compounds. Specifically, they showed that in the Gd(COj Ni )2 system the Co moment appears to be criticaUy dependent on the number and type of its nearest neighbours. Ichinose (1987) measured the NMR of " Al, Mn, " Co and Gd in Gd(X, Coj2 for X = Al, Mn, Fe and Ni. He found from the analysis of the NMR spectra that the concentration dependence of the Co hyperfine field is proportional to the sum of the conduction electron polarization arising from nearest-neighbour transition atoms and that the Co atoms carry a magnetic moment induced by the neighbouring X atoms. 

The cubic Laves-phase compounds RT2 have been studied intensively in the last decade. The simple structure with a single crystallographic site for the R and T ions makes these compounds especially suited for an extensive analysis of the basic magnetic interaction as a function of the lanthanide elements and of the 3d partner. In RC02, a... 

Nuclear magnetic resonance in the magnetically ordered state of rare-earth Laves phase compounds. 

Nuclear magnetic resonance in the magnetically ordered state of rare earth intermetallic compounds excluding Laves phase compounds. Unless noted, the temperature is 4.2 K. 

Important theoretical developments have also been obtained for metamagnetism in multisublattice magnets. However, these improvements have been performed for multisublattice materials with different localized spin subsystems and a single subsystem of the itinerant electrons. Again, this is only the case of the Laves phase compounds but is not the case of the Co-rich compounds. In order to solve this problem, the band calculations are needed which can describe separately the magnetic behaviour for each d subsystem. 

From an experimental point of view, it appears that the resonant f level is the best starting hypothesis for most U, Np and Pu compounds. Only in some cases of strong hybridization (particularly for Laves phase and AuCua-type structure intermetallics) it will broaden into true bands and we shall try to give criteria for itinerant magnetism. 

There are several dozen metallic AB2 compounds called Laves phases that are superconducting they have either cubic or hexagonal crystal structures. Some have critical temperatures above 10 K and high upper critical magnetic fields Bc2- For example, Zri/2Hfi/2V2 has rc = 10.1K, B 2 = 24 T, and a compound with a different Zr/Hf ratio has similar and Bc2 values with the critical current density Jc 4 X 10 A/cm. These materials also have the advantage of not being as hard and brittle as some other intermetallics and alloys with comparable transition temperatures. 

RNi2 compounds crystallize in the cubic Laves phase structure. Because of the simplicity of structure and the ease of preparation and characterization these materials have been extensively studied. From magnetic studies of this family of compounds, Skrabek and Wallace (55) established that nickel moment is zero in the ordered state and moreover that the moment of the rare earth atom is considerably reduced in comparison to that expected for a free trivalent rare earth ion. Bleaney (86) and Skrabek and Wallace (55) have interpreted this decrease in the saturation moment as arising from partial crystal field quenching of the orbital contribution to the total moment. In this respect the RNi2 compounds behave like the RA12 compounds described in an earlier section above. 

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