Neutron diffraction studies of the magnetic phase transitions in Ce_(2)Fe_(17) compound under pressure

摘要

The influence of hydrostatic pressure (up to 5 kbar) on the magnetic structure of Ce_(2)Fe_(17) 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, m_(Fe)=2.0 μ_(B), 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 τ_(1)=0.026 A~(-1) at 100 K to τ_(1)=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 τ_(2)≈0.078 A~(-1) at 40 K under pressures above 3 kbar. The correlation with recent results of magnetization studies under pressure is analyzed and discussed.