High-Field Magnetization Measurements for a Single Crystal of Er2Fe17H3 Hydride (original) (raw)
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METALLIC HYDRIDES.Magnetic properties of laves-phase rare earth hydrides
Le Journal de Physique Colloques, 1979
Neutron scattering results show that the introduction of hydrogen into RFe 2 compounds (R = Tm, Ho, and Er) significantly lowers the overall Curie temperature and produces a reduced 0 K moment on the rare earth site. The rare earth spins disorder at a temperature lower than the bulk T c in ErFe 2 H 35. The 0 K iron sublattice moment in ErFe 2 H 3 5 is essentially the same as that found in the non-hydride compounds and remains nearly constant to approximately 0.8 T c .
The magnetocaloric effect in hydrogen-doped Nd2Fe14B and Er2Fe14B intermetallic compounds
Doklady Physics
The nature of the magnetocaloric effect (MCE) in compounds R 2 Fe 14 B (R = Nd, Er) and their hydrides in a wide temperature range is investigated. The investigation is carried out on initial samples of a special purity including single-crystalline ones. The highest value of the magnetocaloric effect is established in the Curie-temperature region. The hydrogenation of samples affects the value of the MCE. The model explaining the dependence of the value and sign of the magnetocaloric effect on the hydrogen contents in R 2 Fe 14 B compounds with participation of erbium and neodymium is proposed.
Journal of Alloys and Compounds, 2002
The effect of hydrogenation on the magnetic properties of the intermetallic compound ErFe Ti are studied. Single crystals of the 11 hydrogen-containing compound were obtained. Magnetic characteristics of the ErFe Ti and ErFe TiH single crystals have been 11 11 investigated in the temperature range 4.2-750 K and in magnetic fields up to 13 kOe. Upon hydrogenation, the uniaxial magnetic anisotropy is observed to increase, while the spin-reorientation temperatures T shifted towards lower temperatures.
Structural, electronic and magnetic properties of ErFeMn and ErFeMnH 4.7 compounds
New Journal of Physics, 2007
ErFeMn intermetallic alloy after exposure to high hydrogen pressure transformed into the ErFeMnH 4.7 hydride. Both parent material and hydride were investigated for their structural, electronic and magnetic properties by synchrotron XRD (x-ray diffraction), XANES (x-ray absorption near edge structure) and SQUID (superconducting quantum interference device), respectively. Hydrogenation did not change the structure symmetry but caused large expansion of the lattice parameters. Mn and Fe K-edge XANES study of the parent alloy and its hydride reveals that charge on both Mn and Fe atoms remains the same and slightly increases after hydrogenation. Hydrogenation of ErFeMn alloy also caused decrease in the magnetic moment.
Structural and magnetic properties of Dy2Fe17Hx ( and 3) single crystals
Journal of Alloys and Compounds, 2005
The effect of hydrogen on structural and magnetic properties of the Dy 2 Fe 17 H x single crystal was investigated. The host alloys symmetry is retained upon hydrogenation. It was found that the magnetic characteristics (such as the Curie temperature and magnetocrystalline anisotropy) are highly sensitive to the presence of hydrogen and exhibit dramatic changes with changing of H content. The results are discussed in terms of a model considering the interaction of the quadrupole and 4f electron magnetic moments of the rare-earth ion with the interstitial hydrogen atoms.
Hydrogen induced structural and magnetic transformations in the hexagonal Laves phase ErMn2
Journal of Alloys and Compounds, 2004
Powder samples of hexagonal Laves phase ErMn 2 H x hydrides, with 0 < x ≤ 4.3, are characterised by X-ray analysis and SQUID magnetometry for temperatures ranging between 2 and 375 K. Structural transformations as function of the hydrogen concentration and temperature were observed. In particular, a decomposition of spinodal type has been found. It has been shown that structural transformations are reflected in the magnetic behaviour and that an increase of the Mn-Mn distance above the critical distance causes appearance of Mn magnetic moments. The analysis of the magnetic data as function of the hydrogen content, temperature and magnetic field shows that the Mn magnetic moments are antiferromagnetically coupled. The behaviour of these hydrides is compared with the properties of cubic hydrides.
The description of basic experiments of the rare-earth hard magnetic materials, high-field magnetization curves on single-crystalline samples of Ho 2 Co 17 and Nd 2 Fe 14 B is reviewed with the aim to derive parameters physically relevant on atomic scale. The anisotropic magnetic properties have been found to be of single-ion origin. The successful description of the rare-earth compounds Ho 2 Co 17 , Nd in terms of the crystal-field, spin–orbit and inter-site magnetic interactions proves the existence, in a solid, the discrete atomic-like low-energy electron structure that predominantly governs the magnetic and electronic properties. The macroscopic properties have been correlated with the atomic-scale parameters. These studies reveal the importance of the low-symmetry crystal-field interactions (high-order charge multipolar interactions) in description of the magnetic properties of 4f compounds. r
Magnetovolume and magnetocaloric effects in Er_{2}Fe_{17}
Physical Review B, 2012
Combining different experimental techniques, investigations in Er 2 Fe 17 show that this material exhibits a spontaneous magnetostriction that reaches 1.6 × 10 −2 at 5 K and goes down to zero well above the Curie temperature, T C , owing to short-range magnetic correlations. Besides, Er 2 Fe 17 exhibits direct and inverse magneto-caloric effects (MCE) with moderate isothermal magnetic entropy, ∆S M , and adiabatic temperature, ∆T ad , changes (∆S M ∼ −4.7 J/kgK and ∆T ad ∼ −2.5 K near T C , and ∆S M ∼ 1.5 J/kgK and ∆T ad ∼ 0.6 K at 40 K for ∆H = 80 kOe, respectively). The existence of an inverse MCE seems to be related to a crystalline electric field-level crossover in the Er-sublattice and the ferrimagnetic arrangement between the magnetic moments of the Er-and Fe-sublattice. The main trends found experimentally for the temperature dependences of ∆S M and ∆T ad , as well as for the atomic magnetic moments, are qualitatively well described considering a mean field Hamiltonian that incorporates both crystalline electric field and exchange interactions. However, the discrepancies occurring in the temperature range (110 K, 250 K), where the experimental ∆S M and ∆T ad are almost zero and the theoretical curves show a unique cutoff, and the fact that the cell volume of Er 2 Fe 17 exhibits an almost constant value in the same temperature range, lead to the conclusion that the interplay between MCE and magneto-volume anomalies is fundamental to understand the physical properties of this intermetallic compound. PACS numbers: 61.05.C-, 61.05.F-, 75.10.Hk, 75.30.Kz, 75.30.Sg.
Physica B+C, 1985
Commercially procured rare earth metals frequently contain 2-5 atomic per cent oxygen. Rare earth intermetallic compounds prepared from these materials with compositions estimated by synthesis can significantly deviate from the intended composition. Several R2Fe,aB systems have been synthesized using rare earth metals obtained from the Ames Laboratory which typically contain < 25 ppm oxygen (by weight) and their fundamental magnetic properties determined. Curie temperatures range from 565 (for Y2Fet4B) to 669 K (for Gd2Fe,4B). Anisotropy fields (2(1 C) range from 27 to 71 kOe. Results for Y~Fe,4B and Gd2Fe,4B suggest that about 40% of the anisotropy in Nd2Fe,4B originates with the Fe sublattice. The Fe moment in these systems exceeds by a small margin that of elemental Fe. suggesting that B is acting as an electron donor. The Nd moment in Nd2Fe~4B is estimated as 3.0 p.,, which is 92% of the free ion moment. The Nd-Fe and Gd-Fe couplings are ferromagnetic and antiferromagnetic, respectively. Coupling for these systems conforms to the systematics observed earlier for simpler rare earth intermetallics.
Influence of hydrogenation on the magnetic properties of Er2Ni2Al
Chemistry of Metals and Alloys, 2016
The magnetic properties of Er 2 Ni 2 Al and Er 2 Ni 2 AlH 5.3 have been studied in the temperature range 2-300 K. Er 2 Ni 2 Al is an antiferromagnet with T N = 5 K, as indicated by a pronounced maximum in the temperature dependence of the magnetic susceptibility in magnetic fields below 1 T. In the paramagnetic region, the susceptibility is described by the Curie-Weiss law, yielding an effective moment of 9.69 µ B /Er and θ p =-14 K. The field dependence of the magnetization in the ordered state exhibits a metamagnetic transition around 2 T with a relatively wide hysteresis. The hydride Er 2 Ni 2 AlH 5.3 does not show any magnetic ordering above T = 2 K. The Curie-Weiss law fit of the magnetic susceptibility curve yields the values 9.63 µ B /Er and θ p =-10 K. The magnetic behavior of both Er 2 Ni 2 Al and Er 2 Ni 2 AlH 5.3 is supported by the shape of the temperature dependence of the heat capacity curves. The upturn in C/T vs. T for Er 2 Ni 2 AlH 5.3 , which is suppressed by an applied magnetic field, is suggestive of magnetic ordering at still lower temperatures. The dramatic suppression of Er-Er exchange interactions (the size of the Er moments is generally stable) can be understood as a consequence of H bonding, which reduces the concentration of conduction electrons.