Giant X-Ray Circular Dichroism in a Time-Reversal Invariant Antiferromagnet

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spectroscopy

Background:

• X-ray circular dichroism (XCD) is crucial for probing magnetism and chirality.
• Antiferromagnets with chirality usually show weak XCD due to time-reversal symmetry.
• Existing methods struggle to detect magnetic properties in certain chiral antiferromagnets.

Purpose of the Study:

• To report the observation of giant X-ray natural circular dichroism (XNCD) in Ni3TeO6.
• To explain the origin of this phenomenon using a proposed phenomenological model.
• To establish Ni3TeO6 as a new class of magnetic materials with significant circular dichroism.

Main Methods:

• X-ray absorption spectroscopy at the Ni L3-edge.
• Analysis of crystallographic chirality and polar properties of Ni3TeO6.
• Development of a phenomenological model linking photon movement, crystal symmetry, and X-ray polarization.

Main Results:

• Observed giant XNCD in the Ni L3-edge X-ray absorption spectrum of Ni3TeO6.
• Demonstrated that Ni3TeO6 exhibits altermagnetism, a form of magnetism allowed by its symmetry.
• The proposed model successfully explains the coupling of X-ray polarization with induced magnetization.

Conclusions:

• The findings highlight the interplay between magnetism and crystal chirality in natural optical activity.
• Ni3TeO6 represents a novel class of materials exhibiting significant circular dichroism under time-reversal symmetry.
• This work opens new avenues for exploring magnetic properties in chiral materials.