| AVS 66th International Symposium & Exhibition | |
| Actinides and Rare Earths Focus Topic | Tuesday Sessions |
| Session AC+AS+LS-TuM |
| Session: | Chemistry and Physics of the Actinides and Rare Earths |
| Presenter: | Evgeniya Tereshina-Chitrova, Charles University, Prague, Czech Republic |
| Authors: | E.A. Tereshina-Chitrova, Charles University, Prague, Czech Republic L. Havela, Charles University, Prague, Czech Republic M. Paukov, Charles University, Prague, Czech Republic M. Dopita, Charles University, Prague, Czech Republic L. Horak, Charles University, Prague, Czech Republic M. Cieslar, Charles University, Prague, Czech Republic Z. Soban, Institute of Physics, Academy of Sciences of the Czech Republic T. Gouder, Joint Research Center, European Commission, Germany F. Huber, Joint Research Center, European Commission, Germany A. Seibert, Joint Research Center, European Commission, Germany |
| Correspondent: | Click to Email |
Metallic 5f materials have a very strong coupling of magnetic moments and electrons mediating electrical conduction. It is caused by strong spin-orbit interaction together with involvement of the 5f states in metallic bonding. In this work we investigate the electrical resistivity ρ(T) of various uranium-based thin films using the Van der Pauw method. Thin film samples of U-Mo and their hydrides were prepared by reactive sputter deposition [1]. The basic in-situ diagnostics was performed using a photoelectron spectroscopy (XPS). The films were further characterized using x-ray diffraction (XRD) methods and Transmission Electron Microscopy (TEM). The ρ(T) of the films studied correspond to known bulk systems of equivalent composition but provide much more variability of concentrations and geometries.
We studied superconductivity in the U-Mo films by measuring low-temperature resistivity down to 0.4 K. The 100 nm-thick U0.79Mo0.21 film shows a transition to the superconducting state at 0.55 K. The transition is wide and extends to 0.4 K. The upper critical field for the thin U-Mo film is ~1 T, i.e. much lower that for the bulk U-Mo obtained by splat cooling [2].
The hydrides of the U-Mo films had to be prepared using a cooled substrate (≈ 177 K). The study of the (UH3)0.74Mo0.26 of estimated thickness 210 nm showed that it is a ferromagnet with the Curie temperature of ≈165 K, i.e. equivalent to bulk UH3, which underlines the general insensitivity of U hydrides to structure modifications. Overall temperature dependence is very weak and the absolute value of 2 mΩcm, estimated from the nominal thickness, is very high for a metallic system.
The net negative resistivity slope in the U-Mo films and hydrides can be attributed to the randomness on atomic scale, yielding very strong scattering of electrons and weak localization. In the hydrides it is supported also by random anisotropy, randomizing local directions of U moments.
The work is supported by the Czech Science Foundation under the project #18-02344S. Part of the work was supported by “Nano-materials Centre for Advanced Applications,” Project No.CZ.02.1.01/0.0/0.0/15_003/0000485, financed by ERDF.
[1] Gouder, R. Eloirdi, F. Wastin, E. Colineau, J. Rebizant, D. Kolberg, F. Huber, Phys.Rev. B 70, 235108 (2004).
[2] N.-T. H. Kim-Ngan, S. Sowa, M. Krupska, M. Paukov, I. Tkach and L Havela, Adv. Nat. Sci: Nanosci. Nanotechnol. 6, 015007 (2015).