修改第一段
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@@ -89,4 +89,6 @@ This was confirmed by the results under different polarization configurations an
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对齐:正入射、xyyx 使用 E23 对齐,其它则无法对齐,看情况处理。
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只考虑了沿 zOx 平面入射的情况。
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#include "figure-e1.typ"
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@@ -2,26 +2,29 @@
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// 第一段:弱极性与强极性声子模式表现截然不同。如图所示,弱极性声子模式几乎不依赖于波矢方向,而强极性声子模式则表现出显著的各向异性。
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Owing to the distinct behaviors arising from different electrical polarities of Raman-active phonon modes,
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they were categorized into two groups:
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negligible-polarity phonons (i.e., having zero or very weak electrical polarity),
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and strong-polarity phonons.
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The negligible-polarity phonons exhibited minimal dependence on the wavevector direction
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(see the intersection of gray solid lines and orange dashed lines in @figure-discont b and c,
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where the frequency only differed #sym.tilde 0.1 cm#super[-1] across different incidence configurations),
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and were therefore usually analyzed at the #sym.Gamma point regardless of the incidence configurations;
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specifically, there were eight such modes
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labeled A#sub[1]-1 to A#sub[1]-2, E#sub[1]-1 to E#sub[1]-2, and E#sub[2]-1 to E#sub[2]-4,
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according to their irreducible representations in the C#sub[6v] group and in order of increasing frequency.
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In contrast, the strong-polarity phonons displayed significant anisotropy
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(see the intersection of colored solid lines and orange dashed lines in @figure-discont b and c,
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where the frequency differed #sym.tilde 10 cm#super[-1] across different incidence configurations),
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and required analysis under specific incidence configurations.
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In this paper, we focused on incidence within the zOx plane,
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where three modes were present and named according to their vibration directions:
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TO-zOx (vibrating in the zOx plane and roughly perpendicular to the incidence direction),
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Raman-active phonon modes were categorized into two groups,
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according to the distinct behaviors arising from different electrical polarities,
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including eight negligible-polarity modes (i.e., having zero or very weak electrical polarity),
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and three strong-polarity modes.
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The negligible-polarity modes exhibited minimal dependence on the wavevector direction,
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while the strong-polarity modes showed significant anisotropy.
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This distinction was clearly illustrated in @figure-discont,
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where the phonon dispersion relations of negligible-polarity modes (gray solid lines)
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were roughly continuous and flat at the #sym.Gamma point,
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leading to only #sym.tilde 0.1 cm#super[-1] frequency variations and similar vibration patterns
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across different incidence configurations.
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In contrast, the strong-polarity modes (colored solid lines) displayed discontinuities at the #sym.Gamma point,
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resulting in #sym.tilde 1 cm#super[-1] frequency shifts and distinct different vibration patterns
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under different incidence configurations.
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Consequently, the negligible-polarity modes were named
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according to their irreducible representations at the #sym.Gamma point and in order of increasing frequency,
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including A#sub[1]-1 to A#sub[1]-2, E#sub[1]-1 to E#sub[1]-2, and E#sub[2]-1 to E#sub[2]-4.
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In contrast, the strong-polarity modes were named according to their vibration directions and incidence configurations,
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including TO-zOx (vibrating in the zOx plane and roughly perpendicular to the incidence direction),
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TO-y (vibrating along the y-axis), and LO (vibrating roughly parallel to the incidence direction).
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#include "figure-discont.typ"
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In order to further investigate the frequencies dependence on the wavevector,
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and to confirm the accuracy of both our experiments and calculations,
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we analyzed the negligible-polarity phonons off the #sym.Gamma point
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@@ -36,7 +39,7 @@ The E#sub[2]-3 peak served as a calibration reference under various experiments,
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=== Negligible-polarity Phonons
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#include "figure-discont.typ"
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#include "figure-raman.typ"
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Peaks corresponding to seven Raman-active negligible-polarity phonons were observed in our experiments
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