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arXiv 2202.08015cond-mat.str-el
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中间Na层晶体结构驱动的二维蜂窝状层状Na2Ni2TeO6化合物的磁性

Magnetism of the 2D honeycomb layered Na2Ni2TeO6 compound driven by intermediate Na-layer crystal-structure

A. K. Bera, S. M. Yusuf, L. Keller, F. Yokaichiya, J. R. Stewart

摘要:

用中子衍射和中子非弹性散射研究了二维层状结构的自旋1蜂窝晶格化合物Na_2Ni_2 Te_O_6的微观自旋-自旋关联。蜂窝晶格的自旋-1 Ni 2+离子,在晶体学ab平面,以及沿c轴分离的中间Na层,其晶体结构包含手性核密度分布的Na离子。交替的Na层的手性是相反的。Na层的这种交替手性决定了沿c轴的磁性周期性,在c轴上发现了面内锯齿形AFM结构的up-up-down-down自旋排列,此外,在TN ~ 27.5 K以下发现了上述公度(CM)锯齿形AFM有序态与非公度(ICM)AFM有序态共存。发现ICM态出现在更高的温度~ 50 K,并持续到最低测量温度1.7 K。我们的反向蒙特卡罗(RMC)分析揭示了在整个温度范围1.7-50 K的ICM AFM状态的二维(2D)磁关联(在ab平面内)。此外,通过非弹性中子散射实验和随后的线性自旋波理论分析确定了自旋哈密顿量,揭示了与之字形原子力显微镜基态一致的面内竞争交换相互作用的存在,以及弱的面间相互作用和弱的单离子各向异性.的交换常数的值产生,Na 2Ni 2 TeO 6是位于内的锯齿形AFM相(跨越了很宽的范围内的J2/J1和J3/J1值)的理论相图。因此,本研究提供了一个详细的微观理解的磁相关性,并透露交织的磁结构相关性。

英文摘要:

The microscopic spin-spin correlations in the 2D layered spin-1 honeycomb lattice compound Na2Ni2TeO6 have been investigated by neutron diffraction and inelastic neutron scattering. The honeycomb lattice of spin-1 Ni2+ ions, within the crystallographic ab planes, are well separated along the c axis by an intermediate Na layer whose crystal structure contains chiral nuclear density distributions of Na ions. The chirality of the alternating Na layers is opposite. Such alternating chirality of the Na layer dictates the magnetic periodicity along the c axis where an up-up-down-down spin arrangement of the in-plane zigzag AFM structure is found. Besides, the above described commensurate (CM) zigzag AFM order state is found to coexist with an incommensurate (ICM) AFM state below the TN ~ 27.5 K. The ICM state is found to appear at much higher temperature ~ 50 K and persists down to lowest measured temperature of 1.7 K. Our reverse Monte Carlo (RMC) analysis divulges a two dimensional (2D) magnetic correlations (within the ab plane) of the ICM AFM state over the entire temperature range 1.7-50 K. Further, the spin-Hamiltonian has been determined by carrying out inelastic neutron scattering experiments and subsequent linear spin-wave theory analysis which reveals the presence of competing inplane exchange interactions up to 3 rd nearest neighbours consistent with the zigzag AFM ground state, and weak interplanar interaction as well as a weak single-ion-anisotropy. The values of the exchange constants yield that Na2Ni2TeO6 is situated well inside the zigzag AFM phase (spans over a wide ranges of J2/J1 and J3/J1 values) in the theoretical phase diagram. The present study, thus, provides a detailed microscopic understanding of the magnetic correlations and divulges the intertwining magneto-structural correlations.

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