The magnetoelastic properties of Co-rich Ho(Fe,Co,Ti)12 intermetallic compounds near the spin reorientation transition

The thermal expansion and magnetostriction of Co-rich HoFe11−xCoxTi compounds were investigated; using the strain gauge method in the temperature range 77-560 K, under applied magnetic fields up to 1.5 T. Both linear thermal expansion coefficient and volume magnetostriction of HoFe2Co9Ti exhibit a large anomaly near the spin reorientation transition. In HoCo11Ti sample, this anomaly is only present in the volume curve at the spin reorientation transition. The temperature dependence of anisotropic magnetostriction shows a similar behaviour in both samples. There is no saturation in the isotherm curves of anisotropic magnetostriction in HoCo11Ti compound. In contrast, saturation behaviour starts approximately from T=410 K in HoFe2Co9Ti. The magnetovolume effect in Fe-containing compound at around spin reorientation transition in the maximum available magnetic field is approximately two times larger than that in the other sample. The anisotropic and volume magnetostriction results are discussed in terms of the contribution of magnetostriction attributed to the magnetic sublattices R and T and the local magnetic moment model.