Magnetic Order and Spin Reorientations of RGa (R=Gd,Dy,Ho and Er) Intermetallic Compounds

Abstract

The magnetic structures and spin reorientations of RGa (R = Gd, Dy, Ho and Er) intermetallic compounds have been investigated using neutron powder diffraction and rare earth Mössbauer spectroscopy. The aim has been to determine the magnetic structures of these compounds before and after their spin reorientation transitions and to understand the role of the crystal field and exchange interactions in the spin reorientation mechanism. The results have been compared with those found from previous single-crystal susceptibility measurements on RGa and the recent 119Sn Mössbauer spectroscopy work on Sn-doped RGa compounds. The magnetic structures obtained at low temperatures are a simple collinear ferromagnetic in DyGa, canted ferromagnetic in HoGa and a non-collinear ferromagnetic in GdGa. The spin reorientation in ErGa was also observed by 166Er Mössbauer spectroscopy. These results show that both the crystal field and exchange interactions play an important role in the reorientation mechanism.