Magnetic properties of ErAg

Abstract

Neutron diffraction data from a powder sample of ErAg show two antiferromagnetic transitions at temperatures of 18 ± 1 K and 9.5 ± 0.5 K. The magnetic superlattice reflections for the two structures can be indexed on a tetragonal magnetic cell which has basal plane edges twice that of the chemical cell (am = 2a0) and the same dimension in the unique c-axis direction (cm = c0). Between 18 and 9.5 K the magnetic ordering is similar to HoAg and conforms to a sinusoidally modulated magnetization wave propagating in the 〈100〉 direction with the moments tilted from the c axis at angles ranging from 40° (at 18 K) to 80° (at 10 K). The modulation wavelength of 53 ± 2 Å (7.4am) is incommensurate with the unit chemical cell and is temperature independent. In this incommensurate ordering region the ordered moment increases with decreasing temperature to a maximum value of 6.8μB at T = 10 K. Below 9.5 K, the antiferromagnetic ordering is a commensurate (+ − + −) layer-type structure similar to that of DyAg and TbAg, in which adjacent (110) ferromagnetic planes have oppositely directed moments. The tilt of the moments from the c axis is 85° at T = 9 K and decreases to 75° at T = 4 K. The ordered moment on the Er atom sites is 7.2 ± 0.2μB at T = 4 K.

Incommensurate Magnetic Ordering in ErGa3

“…Neutron diffraction data were taken at approximately one tenth degree temperature intervals over the range 1.96 to 4.43 K. In contrast to earlier work [1], our neutron data do not confirm the previously suggested magnetic structure described by the propagation vector k = {1/2 ± ± t, 1/2 ± ± t, 0}, (t % 0.02). The present model can be derived from the {1/2,1/2,0} structure where the antiparallel (110) sheets of spins have superimposed on them a sinusoidal modulation only along to the [100] axis, similarly as in the case of ErAg [3]. The new model is consistent with experimental data published earlier [1].…”

“…It crystallizes within the cubic AuCu 3 -type structure. Recent single crystal magnetisation measurements revealed that even in absence of external magnetic field, ErGa 3 undergoes two successive transitions: at T 1 % 2.6 K and T 2 in the vicinity of the Ne  el temperature T N = 2.83 K. This behaviour has motivated us to undertake a neutron diffraction study first, on a polycrystalline sample of ErGa 3 . The results of this investigation are reported here.…”

Magnetic hyperfine field at Nd sites in NdAg studied by perturbed angular correlation spectroscopy and ab-initio calculations

“…The observed sinusoidal modulation of the magnetic moments on HoAg and ErAg [7,8] indicates that the RKKY mechanism, due to its oscillatory nature, is acting within these compounds. There is another possibility where the coupling is provided by intra-atomic 4f-5d exchange and direct 5d-5d interaction between the spin polarized 5d-electrons of neighboring rare-earth ions [20].…”

“…The chemical structure of these compounds is cubic of CsCl type and the anti-ferromagnetic order of some compounds in the family, namely NdAg [3], GdAg [4], TbAg [5] and DyAg [6], is characterized by adjacent ferromagnetic planes (11 0) having oppositely directed spins in the [0 0 1] direction [4][5][6]. RAg compounds where R elements are Ho and Er are known to present the same anti-ferromagnetic order but their magnetic moments are also subjected to an incommensurate sinusoidal modulation along the [1 0 0] direction and are tilted against the [0 0 1] direction [7,8]. As Nd is the next to Pr in the lanthanide series and NdAg is the first compound in the RAg family that presents anti-ferromagnetic order [1,3] and has been little investigated so far, a microscopic investigation would help to understand the change in the magnetic ordering at the side of light rare-earth compounds in that family.…”

Thermodynamic assessments of the Ag–Er and Er–Y systems

“…Boer and Perrifor [10] predicted that the minimum value of the enthalpies of mixing of liquid phase in the Ag-Er system is −29 kJ/mol, however, no temperature dependence was given in the work of Boer and Perrifor [10]. Nerson [11] and Kaneko et al [12] found that the AgEr phase is antiferromagnetic with the Neel temperature of 18 K [11] and 18.8 K [12]. Due to too low Neel temperature, the magnetic contribution of the AgEr phase to the Gibbs free energy was too small and considered neglectable in the present work.…”