Pressure variations of the 5f magnetism in UH3

Prchal, J.; Buturlim, V.; Valenta, Jaroslav; Dopita, Milan; Diviš, M.; Turek, I.; Kývala, Lukáš; Legut, Dominik; Havela, L.

doi:10.1016/j.jmmm.2019.165993

Cited by 6 publications

(5 citation statements)

References 36 publications

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“…These features of the DFT + U method put constraints on the additional parameters, namely Coulomb U and Hund J, that enter the DFT + U exchange-correlation functional. It turns out that the lattice parameter estimated by GGA is very close to experiment [25,66] and hence the U value cannot be large. On the other hand, LDA underestimates the lattice parameter and therefore it needs to be combined with a larger U [72].…”

Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 57%

“…The improved stability of alloyed UH 3 while maintaining the strong ferromagnetism brought an opportunity of highpressure study using conventional techniques. In [25] pressures exceeding 3 GPa were applied on (UH 3 ) 0.82 Mo 0.18 . It was found that the T C value decreases with pressure at a rate dT C /dp = −2.05 K GPa −1 , which gives the relative change with respect to volume dlnT C /dlnV = 1.1, which is a similar value like in US, indicating an intermediate 5f delocalization.…”

Section: Uranium Hydrides In a Historical Perspective-structure And M...mentioning

confidence: 99%

“…These results indicate that taking into account Hund J explicitly is at least as important as the Coulomb U, similarly to the so-called Hund's metals [77], the physics of which has been intensively studied in the context of iron-based superconductors. Following this reasoning, we arrive at the most comprehensive DFT + U model for UH 3 (and also UH 2 ) formulated so far, which employs GGA, U = 0.5 eV and J = 0.5 eV, and which describes correctly the lattice parameters, elastic properties as well as magnetism, including the Curie temperature [25,63]. The Hund J = 0.5 eV was calculated from the atomic number Z using the empirical rule J = 0.33 + 0.070(Z−89) [78], the Coulomb U was adjusted to reproduce the experimental lattice constant and magnetic moment of α-UH 3 , see [63] for details.…”

Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 99%

“…It can model only ordered magnetic states or an entirely non-magnetic (spin-restricted) state. The non-magnetic state is a very poor approximation for a paramagnet-the energy difference between a ferromagnet and a paramagnet is due to magnetic exchange, which is of the order of k B T C ≈ 15 meV per U atom, whereas it comes out ≈ 0.25 eV per U atom in GGA and ≈ 0.5 eV per U atom in GGA + U [25,74]. This large energy difference is mainly due to the energy gain associated with the formation of uranium magnetic moments and not with the energy gain due to their ordering.…”

Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 99%

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Hydrogen in actinides: electronic and lattice properties

Havela

Legut

Kolorenč³

2023

Rep. Prog. Phys.

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Hydrides of actinides, their magnetic, electronic, transport, and thermodynamic properties are discussed within a general framework of H impact on bonding, characterized by volume expansion, affecting mainly the 5f states, and a charge transfer towards H, which influences mostly the 6d and 7s states. These general mechanisms have diverse impact on individual actinides, depending on the degree of localization of their 5f states. Hydrogenation of uranium yields UH2 and UH3, binary hydrides that are strongly magnetic due to a 5f band narrowing and reduction of the 5f‐6d hybridization. Pu hydrides become magnetic as well, mainly as a result of the stabilization of the magnetic 5f 5 state and elimination of the admixture of the non‐magnetic 5f 6 component. Ab‐initio computational analyses, which for example suggest that the ferromagnetism of β‐UH3 is rather intricate involving two non‐collinear sublattices, are corroborated by spectroscopic studies of sputter‐deposited thin films, yielding a clean surface and offering a variability of compositions. It is found that valence‐band photoelectron spectra cannot be compared directly with the 5f n ground‐state density of states. Being affected by electron correlations in the excited final states, they rather reflect the atomic (n‐1) multiplets. Similar tendencies can be identified also in hydrides of binary and ternary intermetallic compounds. H absorption can be used as a tool for fine tuning of electronic structure around a quantum critical point. A new direction is represented by actinide polyhydrides with a potential for high‐temperature superconductivity.

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Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 57%

Section: Uranium Hydrides In a Historical Perspective-structure And M...mentioning

confidence: 99%

Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 99%

Section: Computational Studies-toward a Comprehensive Model Of Uhmentioning

confidence: 99%

See 2 more Smart Citations

Hydrogen in actinides: electronic and lattice properties

Havela

Legut

Kolorenč³

2023

Rep. Prog. Phys.

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“…S1 (ESI†), the formation energy of H-vacancies at different H/U atom ratios is calculated with three U eff . 12,23,24 The calculated results show that the deviation of E f is within 0.029 eV, indicating that U eff has less effect on E f . Besides, the electronic structure and spin density of β-UH 3 with different U eff are also checked.…”

Section: Methodsmentioning

confidence: 95%