Elemental engineering: Epitaxial uranium thin films

Springell, R.; Detlefs, Blanka; Lander, G. H.; Ward, R. C. C.; Cowley, R. A.; Ling, Ngai; Goetze, W. D.; Ahuja, Rajeev; Luo, Wei; Johansson, Börje

doi:10.1103/physrevb.78.193403

Cited by 23 publications

(37 citation statements)

References 23 publications

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“…We have examined a large number of epitaxial samples, ranging from 70 to 2000Å 14 , and in all cases the CDW appears at a similar T 0 , with similar components, to those reported in Ref. [6]. A comparison to measurements on bulk samples 7 , shows (by normalizing to a lattice peak) that the CDW in U/Nb epitaxial films is reduced in intensity compared to the bulk, and the domain population is heavily biased, unlike in the bulk.…”

Section: A Case Of U/nbmentioning

confidence: 54%

“…2 of Ref. [6] -in all films. However, domain Q 1 is found to have at least 100 times the intensity of domain Q 2 .…”

Section: A Case Of U/nbmentioning

confidence: 79%

“…[6] and above) and found in the bulk 7 , but they are very weak (<1% of the main satellites) and almost certainly arise from strain effects 7 . What is unique about this U/W epitaxy is that the CDW is formed at much higher temperatures than in the bulk, and it appears with just the q x = 0.5 component.…”

Section: B Case Of U/wmentioning

confidence: 84%

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Malleability of uranium: Manipulating the charge-density wave in epitaxial films

et al. 2014

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We report x-ray synchrotron experiments on epitaxial films of uranium, deposited on niobium and tungsten seed layers. Despite similar lattice parameters for these refractory metals, the uranium epitaxial arrangements are different and the strains propagated along the a-axis of the uranium layers are of opposite sign. At low temperatures these changes in epitaxy result in dramatic modifications to the behavior of the charge-density wave in uranium. The differences are explained with the current theory for the electron-phonon coupling in the uranium lattice. Our results emphasize the intriguing possibilities of producing epitaxial films of elements that have complex structures like the light actinides uranium to plutonium.

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Section: A Case Of U/nbmentioning

confidence: 54%

“…2 of Ref. [6] -in all films. However, domain Q 1 is found to have at least 100 times the intensity of domain Q 2 .…”

Section: A Case Of U/nbmentioning

confidence: 79%

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Malleability of uranium: Manipulating the charge-density wave in epitaxial films

et al. 2014

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“…We notice here that the three respective CDW transitions at 42 K (denoted as a 1 transition), 37 K (a 2 ) and 23 K (a 3 ) in the resistivity and specific heat were observed for a-U single crystals [1,2]. We note that although the CDW is hard to be seen in the polycrystalline samples, one can find them in polycrystalline epitaxial films by a very slow cooling through transitions [18].…”

Section: Resistivity and Superconducting Transitionmentioning

confidence: 90%

Characterization of cubic γ-phase uranium molybdenum alloys synthesized by ultrafast cooling

Tkach

Kim-Ngan

Mašková

et al. 2012

Journal of Alloys and Compounds

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“…Epitaxial films of uranium have been made [27,28], and more recently of UO 2 (unpublished). There is no magnetism in uranium, but REXS may be able to help with understanding the interfacial features -up to now efforts have been concentrated on resonant reflectivity and understanding how the induced moments (by hybridisation with neighbouring Fe layers) are distributed within the U layers of the multilayers [29].…”

Section: Conclusion and Future Prospectsmentioning

confidence: 99%

Resonant elastic X-ray scattering from 5f systems

Lander

2012

Eur. Phys. J. Spec. Top.

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Abstract. The first REXS experiments on a uranium compound at the U M 4 edge (3.728 keV) took place at BNL twenty years ago. An enormous enhancement of the scattering intensity was found. Since that time many other systems have been examined. This paper reviews some of the highlights of resonant scattering from actinide systems, and attempts to extrapolate what might be the future of this field.Soon after resonant scattering was discovered at the L edges in Ho [1], it was realised that the strongest effects in resonant elastic X-ray scattering (REXS) could be observed if the transitions involve partially occupied shells with strongly spin-polarised states. Thus the largest resonant effects are found when the L 2,3 edges are used for transition metals of the 3d series, and at M 4,5 (or N 4,5 ) edges for the 4f and 5f series. In the case of the M 4,5 edges of the actinides (5f ) the energies are between 3.5 and 5 keV, so within reach of many diffractometers, without the complications of soft X-rays. Hence the first experiment on UAs [2] at BNL in 1989 found the resonant enhancement to be about 6 orders of magnitude.In the 20 years since this experiment a great many 5f systems have been examined. Some noteworthy highlights are briefly mentioned in this extended abstract.(1) Extension to transuranium materials. At BNL studies were done with NpAs to show both critical scattering and a full examination of the magnetic structure [3,4]. Later, after some difficulties with the crystal surfaces [5], experiments were successfully done on a series of (U 1−x Pu x )Sb single crystals [6,7]. This latter study found an interesting effect at the Pu M 5 edge [7], but this has not been confirmed by XMCD experiments, so its origin remains in doubt. (2) In Ref. [6,7] the element specific nature of REXS was well demonstrated. Another study at ID20 (ESRF) examined alloys of (U 1−x Np x )Ru 2 Si 2 , where the parent compound with x = 0 is the famous heavy-fermion "hidden-order" material, which is still not understood. In REXS study [8] scaling gave a magnetic moment of ∼0.4µ B on the U atom. This was attributed to the large molecular field provided by the ordered Np moments (of 1.5µ B ). It is now known that the large moment state of URu 2 Si 2 does indeed have a moment of this magnitude.

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Elemental engineering: Epitaxial uranium thin films

Cited by 23 publications

References 23 publications

Malleability of uranium: Manipulating the charge-density wave in epitaxial films

Malleability of uranium: Manipulating the charge-density wave in epitaxial films

Characterization of cubic γ-phase uranium molybdenum alloys synthesized by ultrafast cooling

Resonant elastic X-ray scattering from 5f systems

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