Title: Gael Bastien: New triangular lattice antiferromagnets: KCeS2, K0.5RuCl3 and ongoing projects
Number: 26/20
Status: Not exceeded
Begin: Wednesday, 04.11. 2020, 14:10
Tutor: Vladimír Sechovský
Location: ZOOM Meeting ID: 958 0426 7376

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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)




New triangular lattice antiferromagnets: KCeS2, K0.5RuCl3 and ongoing projects

lecture given by:

Gael Bastien

Department of Condensed Matter Physics, Faculty of Mahtematics and Physics, Charles University,
Ke Karlovu 5, 121 16 Prague 2, Czech Republic
Meeting ID: 958 0426 7376 

on Wednesday, 4.11. 2020 from 14:10 CEST (12.10 UTC) 

Passcode will be provided on request at  This e-mail address is being protected from spambots. You need JavaScript enabled to view it


Vladimír Sechovský
On behalf of the DCMP and MGML


Triangular lattice antiferromagnet (TLAF) are valuable due to their magnetic frustration: the impossibility to satisfy simultaneously all the magnetic interactions in the systems. The physics of TLAF was deeply investigated theoretically and experimentally in the case of 3d magnetic ions. However, the choice of heavier magnetic ions such as 4d, 5d or 4f ions bring new possiblities such as the occurence of anisotropic contribution to the magnetic interactions induced by the large spinorbit coupling. These anisotropic magnetic interactions enlarge the variety of possible ground states and may lead to the realization of a quantum spin liquid state, a state of matter with strong magnetic quantum correlations but without any long range magnetic order.

Recently several rare-earth based TLAF were reported. Among them a dozen of rare-earth based TLAF with the delafossite crystal structure such as NaYbS2 are proposed as quantum spin liquid materials. We report here the characteriztion of the compound KCeS2, which despite the same crystal structure as these quantum spin liquid candidates, undergoes a long-range magnetic ordervbelow TN=0.38K [1]. By characterizing this compound and its magnetic order, we can shed light onvthe condition of formation of a quantum spin liquid in TLAF.

The realization of triangular lattice of 4d or 5d magnetic ions are rare. A way to achieve such a triangular lattice is to suppress every second magnetic sites of a honeycomb layered magnet. This was achieved by intercalating K+ ions in the honeycomb magnet alpha-RuCl3 [2]. Indeed, we show signatures of a charge ordering in K0.5RuCl3 leading to a trianguar lattices of magnetic ions Ru3+ (jeff=1/2) and of non magnetic ions Ru2+.

[1] G. Bastien, B. Rubrecht, E. Haeussler, P. Schlender, Z. Zangeneh, S. Avdoshenko, R. Sarkar, A. Alfonsov, S. Luther, Y. A. Onykiienko, H. C. Walker, H. Kühne, V. Grinenko, Z. Guguchia, V. Kataev, H.-H. Klauss, L. Hozoi, J. van den Brink, D. S. Inosov, B. Büchner, A. U. B. Wolter, T. Doert, Scipost Physics 9, 3.041 (2020).

[2] A. Koitzsch, C. Habenicht, E. Müller, M. Knupfer, B. Büchner, S. Kretschmer, M. Richter, J. van den Brink, F. Börrnert, D. Nowak, A. Isaeva, and T. Doert, Phys. Rev. Mater. 1, 052001 (2017).