Infrared spectroscopy study of the nodal-line semimetal candidate ZrSiTe under pressure: Hints for pressure-induced phase transitions

Abstract

We studied the effect of external pressure on the optical response of the nodal-line semimetal candidate ZrSiTe by reflectivity measurements. At pressures of a few GPa, the reflectivity, optical conductivity, and loss function are strongly affected in the whole measured frequency range (200-16500 cm −1 ), indicating drastic changes in the electronic band structure. The pressure-induced shift of the electronic bands affects both the intraband and interband transitions. We find anomalies in the pressure dependence of several optical parameters at the pressures Pc1≈4.1 GPa and Pc2≈6.5 GPa, suggesting the occurrence of two phase transitions of either structural or electronic type.

Effect of Mechanical Strain on the Optical Properties of Nodal‐Line Semimetal ZrSiS

“…after the topological transition has occured. In this regime, ∞ ∼ 3-4, similar to the experimental values reported for ZrSiTe (∼ 3.3) [70]. This result is in favor of the chemical pressure mechanism proposed to describe the difference between the ZrSiX (X=S, Se, Te) family members.…”

“…As it is shown in Figure , the in‐plane component of ε ∞ is remaining around 9–10 up to 1% tension, after which it decreases rapidly until the tension reaches 4%, that is, after the Fermi surface modification has occurred. In this regime, ε ∞ ≈ 3 − 4, similar to the experimental values reported for ZrSiTe (≈3.3) . This result is in favor of the chemical pressure mechanism proposed to describe the difference between the ZrSi X ( X = S, Se, Te) family members.…”

“…Earlier studies on the family of compounds ZrSiX (X=S, Se, Te) suggest that their physical properties are closely connected with the interlayer bonding. Moreover, the ratio of the out-of-plane and in-plane lattice constants c/a can be considered as a measure for the interlayer bonding strength in these systems [13,39,70]. In this regard, uniaxial strain applied in the out-of-plane direction is a promising way to tune the materials' properties.…”

“…In this regard, uniaxial strain applied in the out-of-plane direction is a promising way to tune the materials' properties. Inspired by recent experimental works, which indicate the possibility of a topological phase transition in nodalline semimetals under external pressure [35,70], here we study how the uniaxial strain would affect the optical properties of ZrSiS.…”

Nodal Semimetals: A Survey on Optical Conductivity

“…Measurements of the optical conductivity in ZrSiS have been reported in previous studies. [ 26,84,88,89 ] Figure 4 shows the real part of the optical conductivity obtained in the study by Schilling et al [ 26 ] The striking feature of the spectra is the flat, frequency‐independent, region, spanning from 250 to 2500 cm −1 (30–300 meV) for almost all temperatures investigated (at T ≥ 100 K, the flat region starts at a bit higher frequencies because of a broadened free‐electron Drude mode). This observation is in perfect agreement with the simple‐model predictions for NLSMs discussed above (Equation (1) and (5)).…”