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arXiv 2408.09670cond-mat.str-elcond-mat.mtrl-sci
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三角晶格反铁磁体KErTe2中的有限温度磁性

Finite Temperature Magnetism in the Triangular Lattice Antiferromagnet KErTe2

Weiwei Liu, Zheng Zhang, Dayu Yan, Jianshu Li, Zhitao Zhang, Jianting Ji, Feng Jin, Youguo Shi, Qingming Zhang

AI总结:

本研究针对三角晶格碲化物KErTe2,通过磁化与ESR测量结合平均场近似,确定其CEF参数与交换相互作用,揭示有限温度磁性机制,为后续基态研究提供关键参数。

摘要:

在ARECh2(A=碱金属或一价离子,RE=稀土,Ch=硫族元素)三角晶格量子自旋液体(QSL)家族被发现后,其一系列氧化物、硫化物和硒化物对应物已被陆续报道并得到广泛研究。KErTe2是首个合成的碲化物成员,保留了三角自旋晶格,人们预计大尺寸碲离子可为这类材料带来更显著的磁性特征和电子结构。本研究通过磁化测量和电子自旋共振(ESR),探究了KErTe2在有限温度下的磁性。基于自旋-轨道耦合(SOC)后的角动量$\boldsymbol{\frac{1}{J}}$与对称性分析,我们得到了描述R-3m空间群中Er3+磁性的有效磁哈密顿量。对该哈密顿量应用平均场近似,我们模拟了KErTe2顺磁态的磁化强度和磁热容,并确定了晶体电场(CEF)参数和部分交换相互作用。CEF基态与激发态之间相对较窄的能隙对磁性有显著影响。例如,微小的CEF激发可导致2 K下ESR线宽显著展宽。对于拟合得到的交换相互作用,尽管其数值较小,但考虑到SOC后角动量J=15/2较大,它们在有限温度下仍具有明显作用。值得注意的是,沿c轴方向不同磁场下的热容数据也与我们的计算结果大致吻合,进一步验证了我们分析方法的可靠性。这些推导得到的参数是未来研究KErTe2基态磁性的重要工具。

英文摘要:

After the discovery of the ARECh2 (A=alkali or monovalent ions, RE=rare-earth, Ch= chalcogen) triangular lattice quantum spin liquid (QSL) family, a series of its oxide, sulfide, and selenide counterparts has been consistently reported and extensively investigated. While KErTe2 represents the initial synthesized telluride member, preserving its triangular spin lattice, it was anticipated that the substantial tellurium ions could impart more pronounced magnetic attributes and electronic structures to this material class. This study delves into the magnetism of KErTe2 at finite temperatures through magnetization and electron spin resonance (ESR) measurements. Based on the angular momentum $\hat{J}$ after spin-orbit coupling (SOC) and symmetry analysis, we obtain the magnetic effective Hamiltonian to describe the magnetism of Er3+ in R-3m space group. Applying the mean-field approximation to the Hamiltonian, we can simulate the magnetization and magnetic heat capacity of KErTe2 in paramagnetic state and determine the crystalline electric field (CEF) parameters and partial exchange interactions. The relatively narrow energy gaps between CEF ground state and excited states exert a significant influence on the magnetism. For example, small CEF excitations can result in a significant broadening of the ESR linewidth at 2 K. For the fitted exchange interactions, although the values are small, given a large angular momentum J = 15/2 after SOC, they still have a noticeable effect at finite temperatures. Notably, the heat capacity data under different magnetic fields along the c-axis direction also roughly match our calculated results, further validating the reliability of our analytical approach. These derived parameters serve as crucial tools for future investigations into the ground state magnetism of KErTe2.

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