Polarization-dependent infrared reflectivity study of Sr2.5Ca11.5Cu24O41 under pressure: Charge dynamics, charge distribution, and anisotropy
Polarization-dependent infrared reflectivity study of Sr2.5Ca11.5Cu24O41 under pressure: Charge dynamics, charge distribution, and anisotropy
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压力下 Sr2.5Ca11.5Cu24O41 的偏振相关红外反射率研究：电荷动力学、电荷分布和各向异性
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
C. Kuntscher
中科院分区：
文献类型：
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作者：
S. Frank;A. Huber;U. Ammerahl;M. Huecker;C. Kuntscher
本文研究了自旋梯型化合物Sr_xCa_xCu_xO_xO_的光学响应是强烈的各向异性，具有最高的反射率沿着的梯子/链（E λ c）揭示了金属字符。对于垂直于阶梯面的极化方向，观察到绝缘行为。随着压力的增加，E_（10）c的光学电导率显示出强烈的增加，这在2000 cm ²以下最明显。根据E_（12）c光学电导率的谱权分析，阶梯中的空穴浓度随压力的增加而增加，并在高压下趋于饱和。在~ 7.5GPa时，梯状结构中每个Cu原子的空穴数增加了Δδ=0.09（±0.01），梯状结构中Cu原子价达到+2.33。因此，光学数据表明，Sr Ca Cu O在高压和低温下仍保持高度的电子各向异性。
We present a polarization-dependent infrared reflectivity study of the spin-ladder compound Sr₂₅Ca₁₁₅Cu₂₄O₄₁ under pressure. The optical response is strongly anisotropic, with the highest reflectivity along the ladders/chains (E∥c) revealing a metallic character. For the polarization direction perpendicular to the ladder plane, an insulating behavior is observed. With increasing pressure the optical conductivity for E∥c shows a strong increase, which is most pronounced below 2000cm⁻¹. According to the spectral weight analysis of the E∥c optical conductivity the hole concentration in the ladders increases with increasing pressure and tends to saturate at high pressure. At ~7.5 GPa the number of holes per Cu atom in the ladders has increased by Δδ=0.09(±0.01), and the Cu valence in the ladders has reached the value +2.33. Thus, the optical data suggest that Sr₂₅Ca₁₁₅Cu₂₄O₄₁ remains electronically highly anisotropic up to high pressure, also at low temperatures.