Title: Jiří Pospíšil: Magnetism and magnetic phase diagrams of uranium TiNiSi-type UTGe compounds and their substituted systems
Number: 64/19
Status: Closing date exceeded
Begin: Středa, 13.11. 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

 

Magnetism and magnetic phase diagrams of uranium TiNiSi-type UTGe compounds and their substituted systems

lecture given by:

Jiří Pospíšil

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, 13.11. 2019 from 14:10 

Vladimír Sechovský
On behalf of the DCMP and MGML


Abstract 

Uranium intermetallics with 5f electrons at the boundary between localized and itinerant character are of continuing interest. Recent studies of the TiNiSi-type UTGe compounds found their magnetism scaling according to the Hill criterion1. Just in the vicinity of the Hill criterion ferromagnetic superconductors (FM SC) URhGe2 and UCoGe3 were discovered. Our intensive research in this field was focused on another intriguing compound UIrGe. Although UIrGe has an almost identical the nearest interatomic uranium-uranium distance with URhGe already orders antiferromagnetically4 with Néel temperature TN = 16.5 K. The magnetic structure of UIrGe consists of FM zig-zag chains along the a axis resembling the magnetic structures of the FM UCoGe and URhGe. The FM chains are antiferomagnetically coupled. A spin-flop transition is induced in a magnetic field of Hc,crit = 14 T applied along the c axis. A similar spin flop mechanism was also detected for the magnetization along the b axis at Hb,crit = 21 T. Then, the b axis becomes the easy magnetization axis, similar to the magnetic behavior of FM URhGe. Here, Liftshitz-type transition and enhancement of the coefficient g is observed5, 6 accompanied by restored SC state.

The subject of the seminar is to summarize magnetic properties, phase diagrams and quantum critical phenomena in the parent compounds of the TiNiSi-type UTGe compounds particularly UIrGe under the high pressure7 and magnetic field8 as well as related substituted systems UT11-xT2xGe (T = Co, Rh, Ir, Ru)1, 9-11 which revealed interesting PM/FM/AFM phase boundaries at low temperatures. Our extensive single crystal study has allowed us to draw a general picture of the magnetism in the TiNiSi-type UT11-xT2xGe systems.

1              M. Vališka, et al., Physical Review B 92, 045114 (2015).

2              D. Aoki, et al., Nature 413, 613 (2001).

3              N. T. Huy, et al., Physical Review Letters 99, 067006 (2007).

4              A. P. Ramirez, et al., Journal of Applied Physics 61, 3189 (1987).

5              W. Knafo, et al., Physical Review B 86, 184416 (2012).

6              D. Aoki, et al., Journal of the Physical Society of Japan 81, 011003 (2012).

7              J. Pospíšil, et al., Journal of the Physical Society of Japan 86, 044709 (2017).

8              J. Pospíšil, et al., Physical Review B 98, 014430 (2018).

9              J. Pospíšil, et al., Physical Review B 95, 155138 (2017).

10             J. Pospíšil, et al., Physica B: Condensed Matter 536, 532 (2018).

11             J. Pospíšil, et al., Journal of Applied Physics 105, 07E114 (2009).


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