Magnetic excitations in the helical Rashba superconductor

Area of Science:

• Condensed Matter Physics
• Superconductivity
• Spintronics

Background:

• Noncentrosymmetric superconductors exhibit unique electronic properties due to broken inversion symmetry.
• Rashba spin-orbit coupling significantly influences the superconducting state, leading to helical spin textures.
• Understanding magnetic excitations is crucial for characterizing novel superconducting phases.

Purpose of the Study:

• To investigate the magnetic excitation spectrum in helical superconductors with broken inversion symmetry and strong Rashba spin-orbit coupling.
• To derive general expressions for dynamical spin response functions in such systems.
• To identify characteristic fingerprints of the helical superconducting state.

Main Methods:

• Derivation of dynamical spin response functions.
• Analysis of quasiparticle dispersions in paired and unpaired momentum space regions.
• Inclusion of anomalous coherence factors and spin matrix elements due to helical Rashba spin texture.

Main Results:

• The magnetic response is influenced by excitations within and between paired/unpaired regions.
• Anomalous coherence factors and spin matrix elements contribute to the magnetic response.
• Correlated real-space and spin-space anisotropies arise in the dynamical susceptibility.

Conclusions:

• The study provides a theoretical framework for understanding magnetic excitations in helical superconductors.
• Identified spin anisotropies serve as a characteristic fingerprint for helical superconducting states.
• These findings are potentially observable in inelastic neutron scattering experiments.