Magnetic and structural properties of Lu2(Fe, Mn)17Hy hydrides
The Lu2Fe17−xMnxHy, x = 0–2, y = 0–3, hydrides with the Th2Ni17-type crystal structure were prepared and their structural and magnetic parameters were studied. The lattice parameters measured at room temperature increase smoothly with H content. The magnetic measurements indicate that the Lu2Fe17Hy hydrides (with y up to 1.77) are antiferromagnets at high temperatures and ferromagnets at low temperatures. The Lu2Fe16.5Mn0.5 compound also has a high temperature antiferromagnetic state, but its hydrides are ferromagnets only. The Lu2Fe17−xMnxHy hydrides, with x = 0.7 and 2, are ferromagnets with Tc monotonically increasing with H content. The saturation magnetization measured for Lu2Fe17−xMnxHy, (x = 0,0.5,0.7,2 and 0
Influence of lattice volume on magnetic states of Ce2Fe16MnDy compounds (y=0,1,2.3)
The substitution of Mn for Fe in Ce2Fe17 suppresses its ferromagnetic ground state completely for Mn contents x⩾0.5Mn∕f.u. Ce2Fe16Mn has only an antiferromagnetic phase (incommensurate helix along c axis) below TN=198K. In this paper, we present and discuss the effects of deuterium insertion (that can be considered as an application of negative chemical pressure) on the magnetostructural properties of Ce2Fe16Mn. Application of (positive) high pressures up to 10kbar on Ce2Fe16MnDy deuterides (y=1,2.3) allowed us to estimate the role of lattice volume and to divide it from the role of modified electronic band structure that both determines the magnetic states of the deuterated compounds. The results show that a ferromagnetic phase is stabilized by the insertion of D into the antiferromagnetic Ce2Fe16Mn. The Curie temperature TC of Ce2Fe16MnDy deuterides increases with increasing D content reaching TC=258K for y=2.3 and remarkably decreases with pressure dTC∕dP=−5.4K∕kbar and dTC∕dP=−3.6K∕kbar for Ce2Fe16MnD...
Neutron diffraction studies of the magnetic phase transitions in Ce2Fe17 compound under pressure
The influence of hydrostatic pressure (up to 5 kbar) on the magnetic structure of Ce2Fe17 was investigated using neutron diffraction in the temperature range from 2 to 300 K. The existence of a collinear ferromagnetic phase below 95 K with a magnetic moment of Fe, mFe=2.0 μB, was confirmed at ambient pressure. Magnetic peaks present between 95 and 205 K correspond to an incommensurate antiferromagnetic structure with a wave vector changing its value from τ1=0.026 A−1 at 100 K to τ1=0.034 A−1 at 205 K. A helical model is used to describe the magnetic structure. Application of high pressures leads to significant changes of the magnetic structure. The ferromagnetic phase, suppressed in the studied temperature range by pressures higher than 3 kbar, gets substituted by a new incommensurate antiferromagnetic phase. This phase can be described as a superposition of the helical structure with a second antiferromagnetic coupling with propagation vector τ2≈0.078 A−1 at 40 K under pressures above 3 kbar. The correla...