Field Induced Density Wave in a Kagome Superconductor

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Kagome lattice materials exhibit unique electronic properties due to band topology, flat bands, and Van Hove singularities.
• These properties lead to competing or cooperating electronic orders, with their interrelations being a significant challenge in condensed matter physics.

Purpose of the Study:

• To investigate the electronic behavior of the kagome superconductor KV_{3}Sb_{5} under external magnetic fields.
• To understand the coexistence and interplay of different electronic orders, specifically the charge density wave (CDW) and potential new phases.

Main Methods:

• Experimental measurements including resistivity, nonlinear electrical transport, and angular magnetoresistivity.
• Theoretical modeling using a minimal model for the normal state within the parent CDW phase.

Main Results:

• An unpredicted field-induced phase transition was observed in KV_{3}Sb_{5} below 6 K.
• This transition is characterized by resistivity anomalies, nonlinear transport, and a change in electronic symmetry, suggesting a new broken symmetry state coexisting with the CDW.
• A theoretical model explained the emergence of an incommensurate CDW under suppressed superconducting fluctuations in high magnetic fields.

Conclusions:

• Quantum states in kagome superconductors can coexist or be nearly degenerate in energy.
• KV_{3}Sb_{5} presents a rich platform for exploring new correlated phenomena due to the interplay of multiple quantum states.
• The discovery highlights the complexity of electronic orders in kagome systems and opens avenues for further research into their exotic properties.