Stripe antiferromagnetic ground state of the ideal triangular lattice compound KErSe2
Stripe antiferromagnetic ground state of the ideal triangular lattice compound KErSe2
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DOI：
10.1103/physrevb.103.144413
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发表时间：
2020-06
期刊：
影响因子：
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通讯作者：
J. Xing;K. Taddei;L. Sanjeewa;R. Fishman;Marcus Daum;M. Mourigal;C. Cruz;A. Sefat
中科院分区：
文献类型：
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作者：
J. Xing;K. Taddei;L. Sanjeewa;R. Fishman;Marcus Daum;M. Mourigal;C. Cruz;A. Sefat
稀土三角形晶格材料被认为是研究受挫磁基态的良好平台。KErSe $_2$具有delafote结构，包含完美的二维Er $^{3+}$三角形层，由钾离子分隔，实现了这一理想配置并吸引研究。本文用热容量和中子粉末衍射法研究了KErSe $_2$在毫开尔文温度下的磁性。热容结果显示，在0.2 K处，外加磁场为零，发生了磁跃迁。在0.08 K以下0.5 T的磁场作用下，这种长程顺序被抑制。中子粉末衍射表明，零场磁结构以$k=(\frac{1}{2},0,\frac{1}{2})$为序，呈条形自旋结构。出乎意料的是，我们发现，在有序状态下，Er的矩减小为3.06(1)$\mu_B$ /Er，并且发现，在较高温度下产生的漫射磁散射在有序状态下持续存在，这可能表明磁波动。在外加磁场下收集的中子衍射显示，在$\sim$ 0.5 T时，超磁跃迁到$k$ =(0,0,0)的铁磁阶，并有两种可能的结构，这可能取决于外加磁场的方向。第一性原理计算表明，零场条纹自旋结构可以用反铁磁三角形晶格中的第一、第二和第三相邻耦合来解释。
Rare earth triangular lattice materials have been proposed as a good platform for the investigation of frustrated magnetic ground states. KErSe$_2$ with the delafossite structure, contains perfect two-dimensional Er$^{3+}$ triangular layers separated by potassium ions, realizing this ideal configuration and inviting study. Here we investigate the magnetism of KErSe$_2$ at miliKelvin temperatures by heat capacity and neutron powder diffraction. Heat capacity results reveal a magnetic transition at 0.2 K in zero applied field. This long-range order is suppressed by an applied magnetic field of 0.5 T below 0.08 K. Neutron powder diffraction suggests that the zero-field magnetic structure orders with $k=(\frac{1}{2},0,\frac{1}{2})$ in a stripe spin structure. Unexpectedly, Er is found to have a reduced moment of 3.06(1) $\mu_B$/Er in the ordered state and diffuse magnetic scattering, which originates at higher temperatures, is found to persist in the ordered state potentially indicating magnetic fluctuations. Neutron diffraction collected under an applied field shows a metamagnetic transition at $\sim$ 0.5 T to ferromagnetic order with $k$=(0,0,0) and two possible structures, which are likely dependent on the applied field direction. First principle calculations show that the zero field stripe spin structure can be explained by the first, second and third neighbor couplings in the antiferromagnetic triangular lattice.