Quantum octets in high mobility pentagonal two-dimensional PdSe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer unique properties tunable by external stimuli.
• Ideal 2D materials for electronics require high mobility, air stability, and large-scale synthesis.
• Atomically thin materials are crucial for next-generation electronic devices.

Purpose of the Study:

• To demonstrate air-stable field-effect transistors (FETs) using few-layer palladium diselenide (PdSe2).
• To investigate the electronic transport properties of PdSe2 FETs at various temperatures.
• To explore the potential of PdSe2 for advanced electronic and spintronic applications.

Main Methods:

• Fabrication of field-effect transistors using few-layer PdSe2 sandwiched between hexagonal boron nitride (hBN).
• Electrical characterization including measurements of saturation current and field-effect mobility at 300 K and 2 K.
• Low-temperature magnetotransport studies to analyze quantum oscillations and degeneracies.

Main Results:

• Demonstrated air-stable PdSe2 FETs with high saturation current (>350 μA/μm).
• Achieved high field-effect mobilities of ~700 cm^2/Vs at 300 K and ~10,000 cm^2/Vs at 2 K.
• Observed unique quantum oscillations with 2-fold spin and 4-fold valley degeneracies, tunable by magnetic fields.

Conclusions:

• Few-layer PdSe2 is a promising 2D material for high-performance, air-stable electronic devices.
• The observed quantum phenomena suggest potential for realizing quantum Hall spin and orbital ferromagnetism.
• PdSe2 transistors offer a platform for exploring novel quantum phenomena and future spintronic applications.