Universal Magnetic Phases in Twisted Bilayer MoTe₂.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Twisted bilayer MoTe2 (tMoTe2) is a key material for studying correlated topological phases.
• Understanding the interplay between magnetism and topology in tMoTe2 as a function of twist angle is crucial.

Purpose of the Study:

• To systematically map the magnetic phase diagram of tMoTe2.
• To investigate the influence of twist angle on magnetism and topology.
• To establish a framework for controlling magnetic order in tMoTe2.

Main Methods:

• Local optical spectroscopy.
• Scanning nanoSQUID-on-tip magnetometry.
• Temperature-dependent measurements.

Main Results:

• Spontaneous ferromagnetism was observed at filling factors ν = -1 and -3 for twist angles between 2.1° and 3.7°.
• A universal, twist-angle-insensitive ferromagnetic phase was identified.
• Robust ferromagnetism at ν = -5 was observed at 2.1° but not at larger twist angles.
• Contrasting twist-angle dependence of Curie temperatures for ν = -1 and -3 suggests distinct electronic interactions.
• No topological gap was detected at ν = -3 despite broken time-reversal symmetry.

Conclusions:

• The study provides a comprehensive magnetic phase diagram for tMoTe2.
• Results highlight a universal ferromagnetic phase insensitive to twist angle.
• Findings offer insights into controlling magnetic order and understanding topological properties in twisted transition metal dichalcogenides.