Tunable Van Hove Singularity without Structural Instability in Kagome Metal CsTi_{3}Bi_{5}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Kagome metals like CsV3Sb5 exhibit complex intertwined electronic orders and instabilities.
• The origins of these exotic orders in kagome metals remain poorly understood.
• CsTi3Bi5 is a newly discovered Ti-based kagome metal analogous to CsV3Sb5.

Purpose of the Study:

• To investigate the electronic properties of CsTi3Bi5 using angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations.
• To compare the electronic behavior of CsTi3Bi5 with CsV3Sb5, particularly concerning the van Hove singularity (vHS).
• To explore CsTi3Bi5 as a complementary platform for studying electronic instabilities in kagome metals.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) on pristine and Cs-doped CsTi3Bi5.
• First-principles calculations to model the electronic structure.
• Tuning the van Hove singularity (vHS) through chemical doping (Cs-doping).

Main Results:

• The van Hove singularity (vHS) in CsTi3Bi5 can be tuned over a broad energy range.
• This tuning of vHS in CsTi3Bi5 occurs without inducing structural instabilities, unlike in CsV3Sb5.
• Electronic structure calculations complement ARPES findings, highlighting key features.

Conclusions:

• CsTi3Bi5 presents a distinct platform compared to CsV3Sb5 for studying electronic instabilities.
• The tunable vHS in CsTi3Bi5 without structural phase transitions is a key advantage.
• This material facilitates a deeper understanding of electronic correlations and instabilities in kagome systems.