arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.01052cond-mat.str-el
收藏

强自旋轨道耦合双层反铁磁体中对称分辨的双磁振子激发

Symmetry-resolved two-magnon excitations in a strong spin-orbit-coupled bilayer antiferromagnet

Siwen Li, Elizabeth Drueke, Zach Porter, Wencan Jin, Zhengguang Lu, Dmitry Smirnov, Roberto Merlin, Stephen D. Wilson, Kai Sun, Liuyan Zhao

摘要:

我们采用偏振拉曼光谱和自旋波计算相结合的方法研究了强自旋轨道耦合(SOC)双层钙钛矿反铁磁体$Sr_3Ir_2O_7$中的磁激发。我们在~ 800 $cm^{-1}$和~ 1400 $cm^{-1}$处观察到两个由磁激发产生的宽拉曼特征。非常规地,~ 800 $cm^{-1}$特征相对于下面的四重($D_{4h}$)晶格是完全对称的($A_{1g}$),其连同其宽线形状明确地排除了单个磁振子激发作为其起源的可能性。相反,~ 1400 $cm^{-1}$功能在$A_{1g}$和$B_{2g}$通道中都显示。通过自旋波和双磁振子散射截面的计算,我们确定了~ 800 $cm^{-1}$(~ 1400 $cm^{-1}$)的特征是由磁振子对从带中心$Γ$点(带边界van Hove奇点X点)激发的双磁振子。我们进一步发现,这种区域中心的两个磁振子散射是独特的双层钙钛矿磁铁主机除了声学分支的光学分支,相比他们的单层同行。这种带心双磁振子模式的对称性不同于用来解释$Sr_3Ir_2O_7$的RIXS磁激发谱中~ 92 meV(742 $cm^{-1}$)能隙的时间反演对称性破缺自旋波隙和相位模式。

英文摘要:

We used a combination of polarized Raman spectroscopy and spin wave calculations to study magnetic excitations in the strong spin-orbit-coupled (SOC) bilayer perovskite antiferromagnet $Sr_3Ir_2O_7$. We observed two broad Raman features at ~ 800 $cm^{-1}$ and ~ 1400 $cm^{-1}$ arising from magnetic excitations. Unconventionally, the ~ 800 $cm^{-1}$ feature is fully symmetric ($A_{1g}$) with respect to the underlying tetragonal ($D_{4h}$) crystal lattice which, together with its broad line shape, definitively rules out the possibility of a single magnon excitation as its origin. In contrast, the ~ 1400 $cm^{-1}$ feature shows up in both the $A_{1g}$ and $B_{2g}$ channels. From spin wave and two-magnon scattering cross-section calculations of a tetragonal bilayer antiferromagnet, we identified the ~ 800 $cm^{-1}$ (~ 1400 $cm^{-1}$) feature as two-magnon excitations with pairs of magnons from the zone-center $Γ$ point (zone-boundary van Hove singularity X point). We further found that this zone-center two-magnon scattering is unique to bilayer perovskite magnets which host an optical branch in addition to the acoustic branch, as compared to their single layer counterparts. This zone-center two-magnon mode is distinct in symmetry from the time-reversal symmetry broken spin wave gap and phase mode proposed to explain the ~ 92 meV (742 $cm^{-1}$) gap in RIXS magnetic excitation spectra of $Sr_3Ir_2O_7$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑