NEUTRON-DIFFRACTION STUDY OF THE FERRIMAGNETIC STRUCTURES OF RFE5AL7 COMPOUNDS WITH R=TB, DY, HO, ER, TM

Long range order of ternary RFe5Al7 (R = Th, Dy, Ho, Er, Tm) intermetallics of ThMn12-type structure is analysed by neutron powder diffraction. Ferromagnetic order is found for both the heavy rare earth and the iron sublattices. Rare earth and iron moments are oriented antiparallel to each other, resulting in ferrimagnetic structures. The ordering temperatures are about 235 K for the Tb, Dy and Tm compounds and about 60 K for the Ho and Er compounds. Magnitudes and orientations of ordered magnetic rare earth and iron moments are determined; a moment modulation is observed in TbFe5Al7. The formation of the ferrimagnetic structures is preceded by short range or frozen magnetic states. The temperature behaviour of the magnetization is discussed.