Long-range magnetic order in the ${\tilde S}=1/2$ triangular lattice antiferromagnet KCeS$_2$
Gaël Bastien, Bastian Rubrecht, Ellen Häußler, Philipp Schlender, Z. Zangeneh, Stanislav M. Avdoshenko, Rajib Sarkar, A. Alfonsov, Sven Luther, Y. A. Onykiienko, H. C. Walker, H. Kühne, Vadim Grinenko, Zurab Guguchia, V. Kataev, H.‐H. Klauß, Liviu Hozoi, Jeroen van den Brink, D. S. Inosov, B. Büchner, Anja Wolter-Giraud, Thomas Doert
Abstract
Recently, several putative quantum spin liquid (QSL) states were discovered in {\tilde S} = 1/2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mover> <mml:mi>S</mml:mi> <mml:mo accent="true">̃</mml:mo> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>1</mml:mn> <mml:mi>/</mml:mi> <mml:mn>2</mml:mn> </mml:mrow> </mml:math> rare-earth based triangular-lattice antiferromagnets (TLAF) with the delafossite structure. In order to elucidate the conditions for a QSL to arise, we report here the discovery of a long-range magnetic order in the Ce-based TLAF KCeS _2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msub> <mml:mi/> <mml:mn>2</mml:mn> </mml:msub> </mml:math> below T_{\mathrm N} = 0.38 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mi>T</mml:mi> <mml:mstyle mathvariant="normal"> <mml:mi>N</mml:mi> </mml:mstyle> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.38</mml:mn> </mml:mrow> </mml:math> K, despite the same delafossite structure. Finally, combining various experimental and computational methods, we characterize the crystal electric field scheme, the magnetic anisotropy and the magnetic ground state of KCeS _2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msub> <mml:mi/> <mml:mn>2</mml:mn> </mml:msub> </mml:math> .