Axial Higgs mode detected by quantum pathway interference in RTe₃

Area of Science:

• Condensed Matter Physics
• Particle Physics

Background:

• The Higgs boson confirmed the standard model, but anomalies suggest further symmetry breaking and undiscovered axial Higgs modes.
• Higgs modes have been observed in magnetic, superconducting, and charge density wave (CDW) systems.
• Characterizing low-energy modes' vector properties is difficult, often requiring advanced techniques beyond standard spectroscopy.

Purpose of the Study:

• To discover and characterize an axial Higgs mode in the charge density wave (CDW) system RTe3.
• To explore the vector properties of collective modes using a novel quantum pathway interference technique.
• To provide evidence for an unconventional CDW state through the identification of an axial vector representation in the Higgs mode.

Main Methods:

• Utilizing the interference of quantum pathways to probe the axial Higgs mode in RTe3.
• Analyzing Raman scattering spectra, which include both symmetric and antisymmetric components due to coupled electronic bands.
• Employing a tight-binding model to accurately capture the behavior of the Raman spectra and the axial Higgs mode.

Main Results:

• Direct discovery of an axial Higgs mode in the CDW system RTe3 (R = La, Gd).
• Observation of constructive and destructive interference in Raman spectra based on light polarization, confirming distinct excitation pathways.
• The antisymmetric component of the Raman scattering tensor provides direct evidence for the axial vector nature of the Higgs mode.

Conclusions:

• The study successfully identified an axial Higgs mode in RTe3, offering a new experimental approach for studying collective quantum modes.
• The findings suggest that the CDW in RTe3 is unconventional, characterized by an axial vector representation.
• This method allows for the measurement of quantum properties of collective modes under less extreme experimental conditions.