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تسجيل مستخدم جديدملاحظة الفونونات الفان دير والز في الطبقة الواحدة من الكوبرات (Bi,Pb)$_2$(Sr,La)$_2$CuO$_{6+delta}$
Observation of van der Waals phonons in the single-layer cuprate (Bi,Pb)$_2$(Sr,La)$_2$CuO$_{6+delta}$
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تكافؤ الطبقات الوسطى Van der Waals (vdW) هو شائع في المواد الثنائية الأبعاد مثل الجرافين والمعادن الانتقالية المشتقات الثنائية، والتي يمكن أن تحدث الطورات الصوتية ذات الطاقة المنخفضة جدا. باستخدام الإشعاع الصلب الذي يتميز بدقة عالية، نكشف عن الطور الصوتي ذو الطاقة المنخفضة جدا على طول عقدة Cu-O في كابريت الحرارة العالية (Bi،Pb)_2 (Sr،La)_2CuO_ {6 + delta} (Bi2201). هذا الطور غير معتمد على الحرارة، بينما ينخفض شدة هذا الطور مع التضخيم وفقا لزيادة قيمة المعامل المحور c. نقارن نتائج التجربة بمحاكاة الديناميكة الكمية الأولية ونحدد الطور الملاحظ الملاحظ كطور فان دير والز، الذي ينبعث من حركة الانزلاق للطبقات المجاورة Bi-O. هذا يشير إلى أن كابريت Bi-based لديه الخصائص الصوتية المشابهة للجرافين والمعادن الانتقالية المشتقات الثنائية، التي يمكن استغلالها لتصميم هيتروستراكتورات جديدة.
Interlayer van der Waals (vdW) coupling is generic in two-dimensional materials such as graphene and transition metal dichalcogenides, which can induce very low-energy phonon modes. Using high-resolution inelastic hard x-ray scattering, we uncover the ultra-low energy phonon mode along the Cu-O bond direction in the high-$T_c$ cuprate (Bi,Pb)$_2$(Sr,La)$_2$CuO$_{6+delta}$ (Bi2201). This mode is independent of temperature, while its intensity decreases with doping in accordance with an increasing c-axis lattice parameter. We compare the experimental results to first-principles density functional theory simulations and identify the observed mode as a van der Waals phonon, which arises from the shear motion of the adjacent Bi-O layers. This shows that Bi-based cuprate has similar vibrational properties as graphene and transition metal dichalcogenides, which can be exploited to engineer novel heterostructures.
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