The magnetic and electronic structures of several rare earth-transition metal intermetallic compounds

The crystallographic and magnetic properties of the LaNi_5–x Fe_x (1 ≤ x ≤ 1.4) and LaNi_5–xMn _x (x = 0, 1, 1.5, and 2) compounds have been studied by x-ray and neutron diffraction, SQUID and Mössbauer spectroscopy (LaNi _5–xFe_x only). All of the samples crystallized in the hexagonal CaCu₅-type structure with space group P6/mmm. Both Fe and Mn atoms preferentially occupy the 3g site in these compounds. The LaNi _5–xFe_x samples exhibit ferromagnetic properties for x ≥ 1.2. The different magnetic behavior observed in LaNi₄Fe suggests the coexistence of both short and long range magnetic ordering. The magnetic structure of LaNi_5–xMn_x for x = 1.5 and 2 is described by a ferrimagnetic model. A ferromagnetic model gives the best fit of the neutron diffraction data for LaNi₄Mn. Calculations of the nearest-neighbor environments suggest that the difference between the magnetic structures of LaNi_5–xMn_x is due to the Mn dilution.; The electronic structures of the LaNi_5–xFe _x compounds with x = 1 and 2 have been modeled by the orthogonalized linear combination of atomic orbitals (OLCAO) method. Calculations of magnetic moments, total energy, which is related to the preference of Fe occupying the 3g site, and total density of states are consistent with the results from SQUID measurements, neutron diffraction data, and Mössbauer spectroscopy. The spin-polarized photoemission measurements did not provide quality data due to a sample magnetization problem caused by the low remanence of the samples. Spin-independent photoemission spectra for YCo₅, NdCo₅, and LaNi_3.65Fe_1.35 are presented.