Kulbakov Anton A, Avdoshenko Stanislav M, Puente-Orench Inés, Deeb Mahmoud, Doerr Mathias, Schlender Philipp, Doert Thomas, Inosov Dmytro S
Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01069 Dresden, Germany.
Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter-ct.qmat, TU Dresden, 01069 Dresden, Germany.
J Phys Condens Matter. 2021 Aug 10;33(42). doi: 10.1088/1361-648X/ac15d6.
Yb- and Ce-based delafossites were recently identified as effective spin-1/2 antiferromagnets on the triangular lattice. Several Yb-based systems, such as NaYbO, NaYbS, and NaYbSe, exhibit no long-range order down to the lowest measured temperatures and therefore serve as putative candidates for the realization of a quantum spin liquid. However, their isostructural Ce-based counterpart KCeSexhibits magnetic order below= 400 mK, which was so far identified only in thermodynamic measurements. Here we reveal the magnetic structure of this long-range ordered phase using magnetic neutron diffraction. We show that it represents the so-called 'stripe-' type of antiferromagnetic order with spins lying approximately in the triangular-lattice planes orthogonal to the nearest-neighbor Ce-Ce bonds. No structural lattice distortions are revealed below, indicating that the triangular lattice of Ceions remains geometrically perfect down to the lowest temperatures. We propose an effective Hamiltonian for KCeS, based on a fit to the results ofcalculations, and demonstrate that its magnetic ground state matches the experimental spin structure.
基于镱和铈的铜铁矿最近被确定为三角晶格上有效的自旋1/2反铁磁体。几种基于镱的体系，如NaYbO、NaYbS和NaYbSe，在测量到的最低温度下都没有长程序，因此被视为实现量子自旋液体的潜在候选物。然而，它们的同结构基于铈的对应物KCeS在低于400 mK时表现出磁有序，到目前为止仅在热力学测量中被确定。在这里，我们使用磁中子衍射揭示了这个长程序相的磁结构。我们表明它代表了所谓的“条纹”型反铁磁序，自旋大致位于与最近邻Ce-Ce键正交的三角晶格平面内。在该温度以下未发现结构晶格畸变，这表明Ce离子的三角晶格在最低温度下仍保持几何完美。我们基于对计算结果的拟合为KCeS提出了一个有效哈密顿量，并证明其磁基态与实验自旋结构相匹配。
