- Volodymyr Buturlim: Uranium in metastable systems: structure, magnetism, superconductivity
- 27. 1. 2021, 14:10
- online (zoom)
- online meetink link (Passcode will be provided on request)
- more information
Abstract:
Uranium hydrides have a long history. Despite being the first discovered actinide ferromagnet [1], the understanding of fundamental properties have been lagging due to the nasty pyrophoric nature. Interesting aspects of electronic properties have been revealed during past few years, which was enabled by research of alloyed UH3 [2,3]. In particular, the metastable form, a-UH3, could be stabilized by Zr alloying, and it was found that basic magnetic features as Tc and ms are very similar to theb-UH3, despite different crystal structures and U-U distances [4]. The role of the transition elements in bonding and magnetism in the development of the two structures and their magnetism is still an open question. In my presentation, I am going to report results of the study of ultrafast-cooled U-Nb and U-Ti alloys and in particular of their hydrides. Characterization of the microstructure and crystal structure was performed by means of X-ray diffraction and advanced electron microscopy techniques (EBSD, EDX). Thermodynamic and transport properties of the materials were studied for a better understanding of the magnetic properties. One specific issue of the U-Ti hydrides is the known existence of the Laves phase UTi2Hx which forms exclusively with hydrogen only [5]. We could prepare it as bulk monolithic hydride, which allowed a thorough study of magnetic, transport, and thermodynamic properties [6]. We show how the U magnetism is tuned by variable H concentration in the range 5-6 H atoms/f.u., which allows to cross the onset of magnetic order. UTi2H6 is ferromagnet with TC = 55 K.
References:
[1] R. Troc, W. Suski, J. Alloys Compd. 219 (1995) 1–5.
[2] J. Prchal et al., J. Magn. Magn. Mater. 497 (2020) 165993.
[3] L. Havela et al., J. Electron Spectros. Relat. Phenomena. 239 (2020) 146904.
[4] I. Tkach et al., Phys. Rev. B. 91 (2015) 115116.
[5] T. Yamamoto et al., J. Nucl. Mater. 170 (1990) 140–146.
[6] V. Buturlim et al., Philos. Mag. 99 (2019) 1881–1898.