PC1-6
Charge-density-wave-induced band modulation in new kagome superconductors AV3Sb5 studied by ARPES
*Takemi Kato1, Yongkai Li2,3, Tappei Kawakami1, Min Liu2,3, Kosuke Nakayama1,4, Zhiwei Wang2,3, Ayumi Moriya1, Kiyohisa Tanaka5,6, Takashi Takahashi1,7,8, Yugui Yao2,3, Takafumi Sato1,7,8,9
- Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan1
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing 100081, China2
- Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems, Beijing Institute of Technology, Beijing 100081, China3
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Tokyo, 102-0076, Japan4
- UVSOR Synchrotron Facility, Institute for Molecular Science, Okazaki 444-8585, Japan5
- School of Physical Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan6
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan7
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan7 Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan 8
- International Center for Synchrotron Radiation Innovation Smart (SRIS), Tohoku University, Sendai 980-8577, Japan9
Kagome lattice which consists of a two-dimensional network of corner-sharing triangles provides an excellent platform for exploring new quantum phenomena arising from electronic correlations and non-trivial band topology. Recently, a family of AV3Sb5 (A = K, Rb, Cs) has been discovered to be a novel kagome superconductor with superconducting transition temperature Tc of 0.92-2.5 K [1-3], although kagome metals rarely become superconductors. AV3Sb5 crystallizes in a layered structure consisting of alternating V-kagome lattice layer with hexagonal arrangements of Sb1 atoms, honeycomb-shaped Sb2 layer, and hexagonal A layer [Fig. 1(a)]. In addition to superconductivity, AV3Sb5 undergoes charge-density wave (CDW) transition at TCDW = 78-103 K, and possibly hosts topological surface states. Although this family attracts much attention because of the possible unconventional nature of CDW and its interplay with superconductivity and nontrivial topology, the electronic states relevant to the CDW formation are under intensive debate and the mechanism of CDW and superconductivity is still far from being established.
In this study, we have investigated the electronic structure of AV3Sb5 by photon-energy-tunable angle-resolved photoemission spectroscopy (ARPES) [4,5] and observed multi-orbital nature of the valence band structure in AV3Sb5 [Fig. 1(b)]. Our high-resolution measurements also revealed a drastic electronic reconstruction and an energy gap opening triggered by the CDW transition. We also report the result of detailed band structure mappings above and below TCDW and discuss the mechanism of CDW and its implication to superconductivity through a comparison with the first-principles band-structure calculations.
[1] B. R. Ortiz et al., Phys. Rev. Mater. 3, 094407 (2019).
[2] B. R. Ortiz et al., Phys. Rev. Mater. 5, 034801 (2021).
[3] B. R. Ortiz et al., Phys. Rev. Lett. 125, 247002 (2020).
[4] K. Nakayama et al., arXiv:2104.08042.
[5] T. Kato et al., submitted.
Figure: (a) Crystal structure of AV3Sb5. (b) ARPES intensity plots along the ΓKM cut for AV3Sb5 measured with hν = 114 eV at 120 K. The inset shows the first Brillouin zone of AV3Sb5.
Keywords: Kagome lattice, Charge density wave, Superconductivity, Band structure
