Title: Jiří Prchal: Pressure influence on physical properties of selected intermetallic compounds
Number: 66/19
Status: Closing date exceeded
Begin: Wednesday, 20.11. 2019, 14:10
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

 

Pressure influence on physical properties of selected intermetallic compounds

lecture given by:

Jiří Prchal

Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 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, 20.11. 2019 from 14:10 

Vladimír Sechovský
On behalf of the DCMP and MGML


Abstract 

Application of external pressure as a thermodynamic variable leading to modification of interatomic distances in the studied material is one of important aspects in the condensed matter studies.
Inspired by new discoveries of phenomena like quantum criticality, pressure-induced superconductivity etc. on one side and supported by raising technical possibilities followed by development and improvement of pressure cells on the other side the requests of high pressure experiments are getting more frequent and rather usual in the life of todays solid state physicist.
Also in the Department of Condensed Matter Physics (DCMP) of Charles University the pressure experiments are on daily schedule.

Several compounds which were of interest on our department recently or in the past will be discussed from point of application of external pressure.
* The structural discontinuity observed in the family of RTX compounds crystallizing in the hexagonal ZrNiAl-type crystal sructure were found to be rather rule for the whole family [1]. Application of pressure quite quickly selects only one of the c/a "phases" [2]. Simultaneously - as studied on the case of TbNiAl - the magnetic measurements under pressure indicate strengthening of the AF ground state upon pressure application [3].
* The phenomenon of parimagnetism appearing above the ferrimagnetic ordering temperature of HoCo2 was subjected to the pressure application. The temperature characterizing this effect, Tf, evolves with pressure in a similar rate as the ordering temperature TC [4]. In addition, the estimated pressure development of the Tf and TC follows a common line with other RCo2 compounds (R=Er, Dy, Tb and Gd). The monotonous Tf vs. TC evolution systematically agrees with the unit-cell volume decreasing due to the pressure application and the lanthanide contraction [5].
* Two uranium based compounds are to be mentioned as well. UPd3 as an exceptional case among U-binaries carrying localized magnetic moment is not showing any sign of delocalization up to 10GPa [6].
The decrease of the Curie temperature of UH3 appears with lower rate (dTc/dp) than expected for the 5f itinerant system. Rather unexpected 5f localization tendencies were deduced from the evaluation of the data [7].

References:
[1] J. Prchal et al., Physical Review B 77 (2008) 134106.
[2] J. Prchal et al., Journal of Physics: Conference Series 500 (2014) 032013.
[3] J. Kastil et al., Journal of Alloys and Compounds 585 (2014) 98-102.
[4] J. Valenta et al., Journal of Physics: Conference Series 500 (2014) 182041.
[5] J. Prchal et al., Acta Physica Polonica A 126 (2014) 288-289.
[6] J. Prchal et al., High pressure research 32 (2012) 208-212.
[7] J. Prchal et al., Journal of Magnetism and Magnetic Materials, in press