掃描式穿隧電流能譜影像術與其應用於狄拉克節線半金屬ZrSiS之研究

蘇志川 ； 莊天明

《真空科技》 31卷4期 (2018/12) Pp. 5-12

摘要

掃描式穿隧電流能譜影像術(spectroscopic-imaging scanning tunneling microscopy, SI-STM)是一個強大的樣品表面檢測技術，它可以在原子尺度下同時量測樣品的表面形貌影像(topo-graph)與能量解析電子態空間分布(energy resolved local density of states map)。利用SI-STM研究狄拉克節線半金屬(Dirac nodal line semimetal) ZrSiS表面與電子結構，我們發現此樣品存在至少兩種不同的表面，而且兩種表面上都分別量測到鑽石型狄拉克能態(diamond-shaped Dirac bulk band)以及狄拉克表面能態(surface band)。更進一步的結果顯示，鑽石型狄拉克能態不會受到不同表面原子的影響而有所變化；但是表面態卻在Si原子表面上顯得較弱，研究發現這是因為形成表面態的電子軌域不同所造成的結果。我們的研究顯示ZrSiS具有獨特的狄拉克能態，並且展示Zr原子d軌域電子對ZrSiS及其相關材料之電子結構的重要影響。

並列摘要

Spectroscopic-imaging scanning tunneling microscopy (SI-STM) is a powerful technique to study quantum materials because it can acquire the surface atomic structure and the energy-resolved local density of states map with atomic resolution simultaneously. Here, we use this technique to study a Dirac nodal line semimetal, ZrSiS. Our measurements reveal two different types of surface termination. Both exhibit a diamond-shaped Dirac bulk band as well as a Dirac surface band. Furthermore, we find the surface spectral weight from the Dirac bulk bands is robust on different type of surfaces. However, the surface bands are weaker on the Si-surface due to the change in the surface orbital composition. Our results demonstrate the unique Dirac line nodes phase and the dominating role of Zr-d orbital on the electronic structure in ZrSiS and the related compounds.