arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2004.02170cond-mat.str-el
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单离子易面各向异性反铁磁体的磁振子谱和电子自旋共振

Magnon spectrum and electron spin resonance in antiferromagnet with large single-ion easy plane anisotropy

Artemiy S. Sherbakov, Oleg I. Utesov

摘要:

基于量子磁体NiCl $_{2}$-4SC(NH $_{2}$)$_{2}$(DTN)及其Br掺杂的DTNX的近期实验,我们提出了在磁有序相中具有大的单离子各向异性的反铁磁体中的光学磁振子分支的理论描述.在1/S展开的框架下,我们导出了具有$Δ(h)$能量和磁场依赖性的光磁振子的解析表达式。结果表明,在线性自旋波近似下,$Δ(h)$是单调的,没有极值,而在1/S修正下,一阶修正使它成为完全不同的函数,在磁有序相中心附近有一个极小值。在ESR实验中观察到后一种行为。此外,我们还证明了$Δ(h)$对系统参数具有非平凡的依赖性。它解决了非弹性中子散射数据之间的差异,在DTNX与小Br浓度的相互作用常数的增长,观察和ESR实验显示几乎没有变化的$Δ(h)$与纯DTN相比。

英文摘要:

Motivated by recent experiments on quantum magnet NiCl$_{2}$-4SC(NH$_{2}$)$_{2}$ (DTN) and its Br-doped counterpart DTNX we propose a theoretical description of optical magnon branch in the antiferromagnet with large single-ion anisotropy in the magnetically ordered phase. In the framework of the 1/S expansion we derive analytical expressions for optical magnon with $\mathbf{k}=0$ energy magnetic field dependence $Δ(h)$. It is shown that in the linear spin wave approximation $Δ(h)$ is monotonic without extrema whereas first order in 1/S corrections makes it drastically different function with a minimum near the center of magnetically ordered phase. The latter behaviour was observed in ESR experiments. Moreover, we show that $Δ(h)$ has nontrivial dependence on the system parameters. It solves the discrepancy between inelastic neutron scattering data where the growth of interaction constants in DTNX with small Br concentration was observed and ESR experiments showing almost unchanged $Δ(h)$ in comparison with pure DTN.

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