Thermal expansion anomalies and spontaneous magnetostriction in RFe11Ti single crystals

摘要

The thermal expansion of single crystals of the tetragonal rare-earth intermetallics RFe11Ti (R = Y, Gd, Tb, Dy or Ho) has been studied by X-ray dilatometry in the range 5-800 K. The spontaneous volume magnetostriction omega(s) at 5K amounts to about 1x10(-2) almost independent of the rare-earth component. At elevated temperatures, omega(s) scales well with the square of the Fe magnetic moment, reflecting the dominant contribution of the Fe-Fe exchange interaction in the magnetostriction phenomena in these intermetallics. The magnetostriction is anisotropic; the basal-plane strain lambda(a) far exceeds the uniaxial strain lambda(c). In compounds with R = Dy or Tb, a transition from a multiaxial to a uniaxial anisotropy with increasing temperature is accompanied by an additional volume effect of about 1 x 10(-3) Magnetostrictive distortion (up to 1 x 10(-3) at 5 K) was observed at low temperatures in the basal plane of TbFe11Ti. [References: 27]