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Semináře

Michal Vališka: Magnetoelastic effects of the uranium-based compounds
Begin: 14.11.2018, 14:10
Location: lecture room F2, first floor Ke Karlovu 5

Sergiu Arapan: Searching for the rare-earth free permanent magnets with structure predicting methods: possibilities and limitations
Begin: 15.11.2018, 13:00
Location: Thursday 15.11.2018 at 13:00, Ke Karlovu 5, Praha 2 in Seminar room F052

Evgenia Chitrova: Structure and Magnetism of U-based Thin Films and Heterostructures
Begin: 15.11.2018, 14:00
Location: Lecture room F2, Facutly of Mathematics and Physics, First floor Ke Karlovu 5, Prague 2

David Wagenknecht: Alloy analogy model: An efficient treatment of finite temperatures from the first principles
Begin: 28.11.2018, 14:10
Location: lecture room F2, first floor Ke Karlovu 5

Frank R. de Boer - ceremony of the honorary degree with title of doctor of Physical and Mathematical Sciences, honoris causa.
Location: https://www.cuni.cz/UK-9340.html

 
Title: Michal Vališka: Magnetoelastic effects of the uranium-based compounds
Number: 46/18
Status: Not exceeded
Begin: Středa, Listopad 14, 2018 at 02:10
Tutor: Vladimír Sechovský
Location: lecture room F2, first floor Ke Karlovu 5


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We have a pleasure to invite you to attend the joint seminar
of the Department of Condensed Matter Physics (DCMP)
and the Materials Growth and Measurement Laboratory (MGML) http://mgml.eu.

 

Program


Magnetoelastic effects of the uranium-based compounds

lecture given by:

Michal Vališka

Charles University, Faculty of Mathematics and Physics, DCMP, Ke Karlovu 5, 12116 Prague 2, Czech Republic

The seminar takes place in the lecture room F2 
of the Faculty of Mathematics and Physics, Ke Karlovu 5, Praha 2
on Wednesday, 14.11. 2018 from 14:10 

Vladimír Sechovský
On behalf of the DCMP and MGML


Abstract 

Strong magnetoelastic coupling is common property of the U-based compounds. The strongest elastic effect is connected with the first-order (typically antiferromagnetic) transitions. These were observed in the insulating UO2[1] and in some metallic monopnictides as UAs and UP[2]. The first-order antiferromagnetic transition is rather rare among uranium intermetallics and can be observed for the limited list of compounds like UPd3[3] or UNiSn[4]. More frequent second-order type of antiferromagnetic transition can be forced to the first-order character by applied external parameters like magnetic field or hydrostatic pressure above the so called tricritical point. Such behavior was recently observed for compounds as UN[5], USb2[6], UIrSi3[7], UIrGe[8] or UAu2Si2[9]. Magnetoelastic phenomena is typically connected with the large anisotropy that is tightly bounded with the magnetic structure of the material. This intimate connection can lead to more or less significant structural distortion specially in the case when propagation of the magnetic structure (or direction of the magnetic moments) is violating the structural symmetry of the compound above the ordering temperature – as was observed in the case of UAu2Si2[9] or U4Ru7Ge6[10] and is believed to take place in the hidden-order phase of URu2Si2.

[1] P. Giannozzi and P. Erdos: J. Magn. Magn. Mater. 67 (1987) 75

[2] J.-M. Fournier and R. Tróc: Handbook on the Physics and Chemistry of the Actinides, ed. A. J. Freeman and G. H. Lander (Elsevier, Amsterdam, 1985) Vol. II, p. 29.

[3] S. W. Zochowski, M. de Podesta, C. Lester and K. A. McEwen: Physica B 206 & 207 (1995) 489

[4] T. Akazawa, T. Suzuki, F. Nakamura, T. Fujita, T. Takabatake and H. Fujii: J. Phys. Soc. Jpn. 65 (1996)

[5] K. Shrestha et al., Scientific Reports 7, 6642 (2017)

[6] R. L. Stillwell et al., Physical Review B 95, 014414 (2017)

[7] J. Valenta et al., Phys. Rev. B 97, 144423 (2018)

[8] J. Pospíšil et al., Phys. Rev. B 97, 144423 (2018)

[9] M. Vališka et al., accepted to Phys. Rev. B (2018)

[10] M. Vališka et al., Phys. Rev. B 97, 125128 (2018)


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