Magnetic properties of aluminum-substituted R-T deuterides Ho_6(Fe,Al)_(23)D_z

摘要

The influence of deuteration on the magnetic properties of aluminum-substituted R_6Fe_(23-x)Al_xD_z compounds (R=Ho,Y;x=0,5;z=10,16) has been investigated by magnetization measurements in the temperature range of 5-350 K under a magnetic field of up to 90 kOe. In comparison to the parent alloys, a large increase of the Fe magnetic moment μ_(Fe), much larger in yttrium than in holmium compounds, is observed upon deuteration. The magnetic exchange coupling N_(Ho-Fe) between the R and Fe sublattices was estimated from the slope of the field-induced transitions of the magnetization M isotherms in the vicinity of the compensation temperature T_(comp). The values of N_(Ho-Fe) and T_(comp) decrease with insertion of deuterium, indicating a weakening in R-T coupling. The different results are analyzed within the frame of the Neel ferrimagnetic model taking into account the noncolinearity of the Ho and Fe sublattices magnetizations. The Ho-Ho and Fe-Fe magnetic interactions and the canting angle θ(θ 10°) are then determined. In Al-substituted deuterides, the presence of the rare-earth Ho "stabilizes" the ferrimagnetism.