Magnetostriction in Rare Earth Intermetallics: Interest,Experiments and Models

Some selected and varied examples of magnetostriction in rare earth (RE) intermetallics, crystalline, poly-crystalline and amorphous, magnetically ordered and disordered, are presented to show the interest and relevance of magnetostriction in order to reveal the underlying basic magnetic interactions, i.e. exchange (EX), crystal field (CEF), and magnetoelastic (MEL) interactions. Among the systems recently or currently studied by us we have chosen: the collinear antiferromagnet PrAg; the closely spaced high lying multiplets SmCo₅ uniaxial ferromagnet; the itinerant hexagonal ferromagnet Y₂Fe₁₇; the random magnetic anisotropy amorphous alloys (Tb _x Gd_1-x)₂ Cu, where we have examples of CEF (large x) and anisotropic exchange (x < 0.02) strictions and the fluctuating valence cubic CeNi₂ compound. In all the situations the experimental results are compared with existent or new developed models, in order to extract information about EX, CEF and MEL interactions.