Ising Superconductivity in Bulk Layered Noncentrosymmetric 4H-NbSe_{2}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Transition-metal dichalcogenides (TMDs) offer diverse quantum states due to multiple polymorphs.
• Monolayer 2H-NbSe_{2} shows promise for Ising superconductivity, but bulk 2H-NbSe_{2} lacks necessary symmetry breaking.
• Ising superconductivity requires specific spin-polarized states arising from broken inversion symmetry.

Purpose of the Study:

• To synthesize and characterize the acentric bulk polymorph 4H-NbSe_{2}.
• To investigate the potential of 4H-NbSe_{2} for hosting Ising superconductivity.
• To explore valley-selective spin-polarized states in bulk TMDs.

Main Methods:

• High-quality single crystal growth of 4H-NbSe_{2}.
• Magnetization and resistivity measurements to probe superconductivity.
• First-principles calculations and symmetry analysis for electronic structure.

Main Results:

• 4H-NbSe_{2} intrinsically breaks inversion symmetry and exhibits valley-selective spin polarization.
• Anisotropic superconductivity observed, with in-plane critical fields exceeding the Pauli limit.
• Calculations confirm significant valley-selective spin splitting, supporting Ising pairing.

Conclusions:

• 4H-NbSe_{2} is a promising bulk material for realizing Ising superconductivity.
• This material provides a robust platform for studying valley-selective phenomena in TMDs.
• The findings open new avenues for quantum device exploration.