Composite Fermi Liquid at Zero Magnetic Field in Twisted MoTe_{2}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Exotic phases of matter are typically found under extreme conditions, like quantizing magnetic fields.
• Recent experiments show fractional Chern insulators in twisted MoTe2 bilayers at zero magnetic field.
• The topological valence band in these materials is key to observing novel quantum states.

Purpose of the Study:

• Investigate the topological valence band at half filling in twisted MoTe2 bilayers.
• Discover new quantum phases of matter at zero magnetic field.
• Understand the properties and experimental signatures of these phases.

Main Methods:

• Utilized exact diagonalization and density matrix renormalization group (DMRG) calculations.
• Analyzed the behavior of twisted MoTe2 bilayers at specific twist angles (∼3.6°).
• Examined the role of quantum geometry and interactions in stabilizing exotic phases.

Main Results:

• Discovered a composite Fermi liquid (CFL) phase at zero magnetic field.
• The CFL phase exhibits metallic behavior without Landau quasiparticles.
• Identified excellent quantum geometry and interaction-reduced bandwidth in the topological valence band.
• Observed competition between CFL and Fermi liquid phases, tunable by a displacement field.

Conclusions:

• The composite Fermi liquid phase is a stable, exotic state in twisted MoTe2 bilayers at zero magnetic field.
• The unique properties of the topological valence band are crucial for stabilizing these zero-field quantum Hall phases.
• An optical signature involving "extinguished" optical responses can detect Chern bands with ideal quantum geometry.