Tunable surface plasmons in Weyl semimetals TaAs and NbAs
Tunable surface plasmons in Weyl semimetals TaAs and NbAs
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DOI：
10.1103/physrevb.99.121401
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发表时间：
2018-11
影响因子：
3.7
通讯作者：
G. Chiarello;Johannes S. Hofmann;Zhilin Li;Vito Fabio;Liwei Guo;Xiaolong Chen;S. Sarma;A. Politano
中科院分区：
文献类型：
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作者：
G. Chiarello;Johannes S. Hofmann;Zhilin Li;Vito Fabio;Liwei Guo;Xiaolong Chen;S. Sarma;A. Politano
利用高分辨电子能量损失谱研究了过渡金属铌酸盐中Weyl费米子的低能激发谱。我们观察到带隙的等离子体激元模式在（001）取向的NbAs和TaAs的单晶表面在66和68 meV，分别。我们的研究结果与理论相一致，我们估计两个样品的有效库仑相互作用强度$\alpha_{\rm eff}\approx0.41 $。我们还表明，通过吸附的化学物种（在我们的情况下，氧和烃片段）的表面的改性的过渡金属nanictides改变的等离子体激元激发的频率，与随后的修改的有效相互作用强度在0.30-0.48的范围内。等离子体特征对吸附物存在的显著依赖性为基于在中红外操作的Weyl半金属的等离子体传感器铺平了道路。
By means of high-resolution electron energy loss spectroscopy, we investigate the low-energy excitation spectrum of transition-metal monopnictides hosting Weyl fermions. We observe gapped plasmonic modes in (001)-oriented surfaces of single crystals of NbAs and TaAs at 66 and 68 meV, respectively. Our findings are consistent with theory and we estimate an effective Coulomb interaction strength $\alpha_{\rm eff}\approx0.41$ for both samples. We also demonstrate that the modification of the surface of transition-metal monopnictides by the adsorption of chemical species (in our case, oxygen and hydrocarbon fragments) changes the frequency of the plasmonic excitations, with a subsequent modification of the effective interaction strength in the 0.30-0.48 range. The remarkable dependence of plasmonic features on the presence of adsorbates paves the way for plasmonic sensors based on Weyl semimetals operating in the mid-infrared.