拓扑材料BaMnSb_(2)的红外光谱学研究  

Infrared spectroscopic study of topological material BaMnSb_(2)

作　　者：邱子阳 陈岩 邱祥冈[2,3,4] Qiu Zi-Yang;Chen Yan;Qiu Xiang-Gang(Nanjing Electronic Device Institute,Nanjing 210016,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Collaborative Innovation Center of Quantum Matter,Beijing 100084,China)

机构地区：[1]南京电子器件研究所,南京210016 [2]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190 [3]中国科学院大学物理学院,北京100049 [4]量子物质科学协同创新中心,北京100084

出　　处：《物理学报》2022年第10期263-268,共6页Acta Physica Sinica

摘　　要：对于新型拓扑材料BaMnSb_(2),研究了从7 K到常温下温度依赖的宽频红外光谱特性.随着温度的降低,绝对反射谱中等离子体极小值有着明显的蓝移,表明载流子浓度存在随温度变化的行为.在光电导谱的实部中存在两段随着频率线性增加的响应,它们的线性外延不经过原点,表明BaMnSb_(2)的费米能级附近有打开能隙的Dirac型色散.此外,在低温下还发现了一段不随频率变化的光电导,且无法用传统的Drude-Lorentz模型拟合.因此本文引入了一个恒定的光电导分量,得到了满意的拟合结果.通过计算和分析,我们认为恒定光电导分量可能来自于拓扑材料BaMnSb_(2)的表面态响应.A detailed infrared optical spectrum of the new topological material BaMnSb_(2)has been measured at temperatures ranging from 7 K to 295 K.As the temperature decreases,the plasma minimum has a clear blue shift in reflectivity spectrum,indicating that the carrier density changes with temperature.In the real part of the optical conductivity σ_(1)(ω),two linearly-increased components can be identified,but neither of their extrapolation pass through the origin,which proves that BaMnSb_(2)has a gapped Dirac dispersion near the Fermi level.Comparing with the theoretical calculation by using first-principles methods,the onset of these two linearly-increased components are in good agreement with the band structures.In addition,a range of constant optical conductivity is found in σ_(1)(ω),which cannot be described well by the Drude-Lorentz model.Therefore,we introduce a frequency-independent component to fit σ_(1)(ω) successfully.However,different from the Dirac nodal-line semimetal YbMnSb_(2)which shares same fitting results as well as crystal structure,the constant component in BaMnSb_(2)has a small proportion of σ_(1)(ω).Through calculation and analysis,we attribute the constant component to the surface state of BaMnSb_(2).

关 键 词：红外光谱 拓扑材料 恒定光电导 

分 类 号：O657.33[理学—分析化学] TQ132.35[理学—化学]