Geometry-Enhanced Second-Harmonic Charge Transport in Kagome Superconductor CsV₃Sb₅

Area of Science:

• Condensed matter physics
• Materials science

Background:

• Layered kagome materials exhibit nontrivial band topology and geometric frustration, leading to correlated states like charge density waves (CDW) and superconductivity.
• Recent studies on CsV3Sb5 suggest potential chirality within these CDW and superconducting states.

Purpose of the Study:

• To investigate chiral phenomena in CsV3Sb5.
• To explore the role of nonuniform current flow in second-harmonic generation (SHG) for detecting chirality.

Main Methods:

• Performed second-harmonic generation measurements with a nonuniform current applied to CsV3Sb5.
• Analyzed nonreciprocal signals observed in the CDW state.
• Subtracted thermoelectric contributions, specifically the Nernst effect, to isolate intrinsic signals.

Main Results:

• Observed distinct nonreciprocal second-harmonic signals in the CDW state of CsV3Sb5.
• Identified residual signals after accounting for thermoelectric effects, indicating chiral scattering under nonuniform current.
• The observed phenomena are analogous to chiral edge states in magnetic topological insulators.

Conclusions:

• The study provides evidence for chiral scattering processes in CsV3Sb5.
• Highlights the significance of device geometry in SHG for observing chiral phenomena in 2D materials.
• Suggests SHG as a valuable technique for probing chirality in correlated electronic systems.