Giant isotope effect on the itinerant-electron metamagnetism inYFe2(HyD1−y

Isotope effect on the thermodynamic and structural properties of Y1−yRyFe2(H,D)x(γ) compounds (R=Tb, Er, Lu; 4.0≤x(γ)≤4.5)

“…These volume differences cannot be related to a difference in capacity, since the deuterides have a larger capacity than the corresponding hydrides. Therefore, this difference should be rather attributed to the difference of the zero point amplitude of vibration of the H and D atoms which is larger for H atoms due to their smaller mass [8,16]. This means that the interstitial sites containing H atoms are more expanded than those containing D atoms and lead to a larger cell volume.…”

“…Thanks to complementary methods, this transition has been attributed to an itinerant electron metamagnetic behavior (IEM) of one of the Fe sites surrounded by about 5 D atoms [7]. Surprisingly this transition is very sensitive to the H for D substitution, which increases the mean Fe moment at 4.2 K and shifts the transition temperature to 130 K (by 50%) [5,8]. Since the cell volume of the hydride is 0.78% larger than the deuteride, this giant isotope effect has been related to the strong dependency of the IEM behavior on the volume [9,10].…”

Effect of hydrogen as interstitial element on the magnetic properties of some iron rich intermetallic compounds

“…An exceptionally large increase of the ordering temperature has been reported upon H for D substitution in the YFe 2 compound. The hydride exhibits a 50% larger transition temperature [44,67]. The insertion of hydrogen or deuterium has been found to lead to different physical properties.…”

Investigation of compounds for magnetocaloric applications: YFe2H4.2, YFe2D4.2, and Y0.5Tb0.5Fe2D4.2

“…24,25 These YFe 2 ͑H 1−y D y ͒ 4.2 compounds crystallize below 340 K in a monoclinic structure, which is due to a lowering of symmetry of the cubic C15 structure of the parent compounds induced by deuterium or hydrogen order in some particular tetrahedral interstitial sites. 26 These compounds undergo a sharp first-order magnetovolumic transition.…”

“…This behavior shows some similarities with that of RCo 2 compounds 27,28 and were attributed to the IEM behavior of one Fe site, which is close to the magnetic instability. 25 The difference in transition temperature has been partially explained by the difference of volume between the hydride and the deuteride. Further studies on the influence of an applied pressure or Y substitution by another rare earth are in progress to determine more precisely the influence on the volume, magnetic and electronic changes on the magnetovolumic transition.…”