Quantum spin liquid ground state in the disorder free triangular lattice NaYbS2

Abstract

Rare-earth delafossites were recently proposed as promising candidates for the realization of an effective S = 1/2 quantum spin liquid (QSL) on the triangular lattice. In contrast to the most actively studied triangular-lattice antiferromagnet YbMgGaO4, which is known for considerable structural disorder due to site intermixing, NaYbS2 delafossite realizes structurally ideal triangular layers. We present detailed µSR studies on this regular (undistorted) triangular Yb sublattice based system with effective spin J eff = 1/2 in the temperature range 0.05 -40 K. Zero-field (ZF) and longitudinal field (LF) µSR studies confirm the absence of any long range magnetic order state down to 0.05 K (∼ J/80). Current µSR results together with the so far available bulk characterization data suggest that NaYbS2 is an ideal candidate to identify QSL ground state.

Long-range magnetic order in the ${\tilde S}=1/2$ triangular lattice antiferromagnet KCeS$_2$

“…KCeS 2 provides an example of a magnetically orderedS = 1/2 TLAF with the delafossite structure, in contrast to the putative QSL candidates NaYbO 2 [21][22][23][24], NaYbS 2 [19,21,26], NaYbSe 2 [21,27], KYbS 2 [29], CsYbSe 2 [30] and CsCeSe 2 [30]. Specific heat measurements of each of these QSL candidates indicate a broad maximum of C p /T around the temperature corresponding to the possible formation of the spin liquid state [19,22,27,29,30].…”

“…For the two magnetic ions Ce 3+ or Yb 3+ , with electronic configurations of 4 f 1 and 4 f 13 , respectively, aS = 1/2 spin state can be achieved at low temperature due to the spin-orbit coupling in combination with the depopulation of higher-energy crystal electric field (CEF) levels [13,14,18,19]. Numerous Ybbased TLAF were recently reported and proposed to host a quantum spin liquid ground state: YbMgGaO 4 [13,20], NaYbO 2 [21][22][23][24][25], NaYbS 2 [19,21,26], NaYbSe 2 [21,27,28], KYbS 2 [29], CsYbSe 2 [30] and Yb(BaBO 3 ) 3 [31]. In addition, a putative QSL state was recently reported in the Ce-based TLAF CsCeSe 2 [30].…”

Magnetic Properties of an Effective Spin-\(\frac{1}{2}\) Triangular-Lattice Compound LiYbS2

“…Quantum spin liquid (QSL), a highly entangled state with fractionalized excitations that evade magnetic long-range order down to zero temperature, has been attracting the attention of condensed matter research for several decades [1][2][3][4]. Yb-based dichalcogenide delafossites AYbX 2 (A = monovalent ion; X = divalent chalcogen ion) are recently reported as the promising candidates for realizing QSL ground states [5][6][7][8][9][10][11][12][13][14][15][16]. Here, the eight fold degeneracy of Yb 3+ ions could be lifted to four Kramers doublets due to the combined effects of strong spin-orbit coupling (SOC) and crystal electric field (CEF).…”

Fluctuating magnetic droplets immersed in a sea of quantum spin liquid

“…Compared with YbMgGaO4, the family of Yb dichalcogenide delafossites NaYb(O, S, Se)2 with effective spin-1/2 is free from the Mg-Ga disorders in non-magnetic layers, thus is of crucial importance to clarify whether there is a QSL ground state in clean triangular lattice of Yb 3+ ions 36,37 . All three compounds are free from long-range order (LRO) down to 50 mK determined from zero field (ZF) specific heat and µSR measurements [37][38][39][40] . Including CsYbSe2 with the same structure, all of them have field-induced magnetic orders 38,[41][42][43][44] .…”