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arXiv 1003.2229cond-mat.str-el
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单晶LaSr $_2$ Mn $_2$ O $_7$的软X射线共振散射研究

Soft X-ray resonant scattering study of single-crystal LaSr$_2$Mn$_2$O$_7$

H. -F. Li, Y. Su, Tapan Chatterji, A. Nefedov, J. Persson, P. Meuffels, Y. Xiao, Th. Brückel

摘要:

报道了单晶LaSr $_2$ Mn $_2$ O $_7$的Mn $L_{\texttt{II, III}}$ -和La $M_{\texttt{IV, V}}$ -边的软X射线共振散射研究。在低温下,低于$T_\texttt{N} \approx 160$ K,能量扫描与一个固定的动量转移在\emph{A}型反铁磁(0 0 1)反射周围的Mn $L_{\texttt{II, III}}$ -边缘与入射线性$σ$和$π$极化表现出强烈的共振增强。Mn $L_{\texttt{II, III}}$ -边缘周围的能谱的分裂可以指示混合价态的存在,例如,Mn $^{3+}$ /Mn $^{4+}$。共振的相对强度和清晰的肩特征以及强的入射$σ$和$π$偏振依赖性强烈表明其复杂的电子起源。在300 K温度下观察到了$σ$极化的La $M_{\texttt{IV, V}}$ -边缘处电荷布拉格(0 0 2)反射的意外增强,在轨道有序转变温度$T_{\texttt{OO}} \approx 220$ K附近出现异常,表明它们之间存在强耦合(竞争)。

英文摘要:

Soft X-ray resonant scattering studies at the Mn $L_{\texttt{II, III}}$- and the La $M_{\texttt{IV, V}}$- edges of single-crystal LaSr$_2$Mn$_2$O$_7$ are reported. At low temperatures, below $T_\texttt{N} \approx 160$ K, energy scans with a fixed momentum transfer at the \emph{A}-type antiferromagnetic (0 0 1) reflection around the Mn $L_{\texttt{II, III}}$-edges with incident linear $σ$ and $π$ polarizations show strong resonant enhancements. The splitting of the energy spectra around the Mn $L_{\texttt{II, III}}$-edges may indicate the presence of a mixed valence state, e.g., Mn$^{3+}$/Mn$^{4+}$. The relative intensities of the resonance and the clear shoulder-feature as well as the strong incident $σ$ and $π$ polarization dependences strongly indicate its complex electronic origin. Unexpected enhancement of the charge Bragg (0 0 2) reflection at the La $M_{\texttt{IV, V}}$-edges with $σ$ polarization has been observed up to 300 K, with an anomaly appearing around the orbital-ordering transition temperature, $T_{\texttt{OO}} \approx 220$ K, suggesting a strong coupling (competition) between them.

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。

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