Twofold Anisotropic Superconductivity in Bilayer T_{d}-MoTe_{2}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Noncentrosymmetric 2D superconductors with strong spin-orbit coupling (SOC) enable exploration beyond the Pauli limit.
• Few-layer Td-molybdenum ditelluride (MoTe2) shows upper critical fields exceeding the Pauli limit by up to 600%.
• The underlying mechanisms for this enhancement are debated, with theories suggesting spin-orbit parity coupling or tilted Ising SOC.

Purpose of the Study:

• To investigate the superconducting behavior of bilayer Td-MoTe2 under in-plane magnetic fields.
• To explore the influence of magnetic field angle and out-of-plane electric fields on superconductivity.
• To determine the dominant SOC mechanism in bilayer Td-MoTe2.

Main Methods:

• Experimental measurements of superconducting properties in bilayer Td-MoTe2.
• Systematic variation of in-plane magnetic field angle and out-of-plane electric field strength.
• Comparison of experimental SOC strength with first-principles calculations.

Main Results:

• Superconductivity in bilayer MoTe2 displays twofold symmetry, with critical field maxima along the b axis and minima along the a axis.
• This twofold rotational symmetry is robust across the superconducting region and ferroelectric hysteresis loop.
• Experimental SOC strength (up to 16.4 meV) aligns with theoretical spin texture and spin splitting.

Conclusions:

• Tilted Ising spin-orbit coupling is identified as the dominant mechanism governing superconductivity in bilayer Td-MoTe2.
• The observed twofold symmetry and its robustness provide critical insights into the interplay of magnetism, ferroelectricity, and superconductivity.
• This study advances the understanding of unconventional superconductivity in 2D materials.