Temperature-Induced Lifshitz Transition and Possible Excitonic Instability in ZrSiSe
The nodal-line semimetals have attracted immense interest due to the unique electronic structures such as the linear dispersion and the vanishing density of states as the Fermi energy approaching the nodes. Here, we report temperature-dependent transport and scanning tunneling microscopy (spectroscopy) [STM(S)] measurements on nodal-line semimetal ZrSiSe. Our experimental results and theoretical analyses consistently demonstrate that the temperature induces Lifshitz transitions at 80 and 106 K in ZrSiSe, which results in the transport anomalies at the same temperatures. More strikingly, we observe a V-shaped dip structure around Fermi energy from the STS spectrum at low temperature, which can be attributed to co-effect of the spin-orbit coupling and excitonic instability. Our observations indicate the correlation interaction may play an important role in ZrSiSe, which owns the quasi-two-dimensional electronic structures. © 2020 American Physical Society. ; This work was supported by the National Key R&D Program (Grants No. 2016YFA0300404, No. 2016YFA0401803, No. 2017YFA0303201, No. 2015CB921103, and No. 2019YFA0308602), the National Nature Science Foundation of China (Grants No. 11674326, No. 11674331, No. 11774351, No. 11874357, No. 11625415, No. 11374260, No. U1432139, No. U1832141, and No. U1932217), Key Research Program of Frontier Sciences, CAS (Grant No. QYZDB-SSW-SLH015), the "Strategic Priority Research Program (B)" of the Chinese Academy of Sciences, Grant No. XDB33030100, the "100 Talents Project" of the Chinese Academy of Sciences, CASHIPS Director's Fund (Grant No. BJPY2019B03) and Science Challenge Project (Grant No. TZ2016001). A portion of this work was supported by the High Magnetic Field Laboratory of Anhui Province, the Fundamental Research Funds for the Central Universities in China, the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) through ERC Grant No. 338957 and by NWO via Spinoza Prize, and the Cluster of Excellence "The Hamburg Centre for Ultrafast Imaging (CUI)" of the German Science Foundation (DFG).