Magnetic structures and transitions of RNiSi₃ (R = Gd-Ho)

Full text: Rare earth-based materials have received considerable attention over the years due to many interesting physical phenomena, such as highly anisotropic magnetic properties associated with the unquenched orbital moments are commonly observed. Recently, a new series of rare earth intermetallic compounds RNiSi₃ (R = Y, Gd-Tm) were synthesized, based on the isostructural compound YbNiSi₃. Magnetic susceptibility measurements indicate antiferromagnetic phases at low temperatures (TN = 2-32 K) with fairly marked anisotropy. However, the magnetic structures, among the different possibilities for an antiferromagnetic ordering, still need to be determined. Knowing that photons are also sensitive to the electronic magnetic moments, leading to the appearance of magnetic Bragg peaks in the ordered phase of the material, we intend to contribute to the characterization and understanding of the magnetism of such systems by means of resonant magnetic X-ray diffraction experiments. These peaks may be strongly intensified when the energy of the X-rays coincides with some absorption edge of the magnetic element, causing a resonant scattering condition. This gives to the technique the advantage of being element-selective and allow us to solve the magnetic structures and investigate the phase transitions induced by temperature and, if possible, magnetic field. The diffraction measurements described above will be carried out at the XDS (X-ray Diffraction and Spectroscopy) beamline of LNLS, starting the second semester of 2017. (author)