Researchers have uncovered the intricate interplay between structural chirality and magnetism in a unique rare-earth ferroborate material, DyFe3(BO3)4. Using advanced X-ray techniques, they were able to separate the contributions of natural circular dichroism (XNCD) and magnetic circular dichroism (XMCD) in this chiral magnet, revealing the independent behavior of the iron and dysprosium magnetic sublattices. Their findings shed light on the complex interplay between structural and magnetic properties in these intriguing materials, which could have important implications for the development of novel spintronic and multiferroic devices.
Unraveling Chiral Magnetism
Structural chirality, the property of an object that cannot be superimposed on its mirror image, is a fundamental concept in chemistry and magnetism, it can lead to unusual and technologically relevant material properties. The rare-earth ferroborate DyFe3(BO3)4 is a prime example of such a chiral magnet, crystallizing in a non-centrosymmetric structure with right- and left-handed screw chains of iron and dysprosium atoms.
Probing Chirality and Magnetism with X-rays
To unravel the interplay between chirality and magnetism in this material, the researchers utilized advanced X-ray techniques, specifically X-ray natural circular dichroism (XNCD) and X-ray magnetic circular dichroism (XMCD). XNCD arises from the difference in absorption of left- and right-circularly polarized X-rays in chiral systems, while XMCD is sensitive to the magnetic ordering of the material.
By carefully deconvolving the XNCD and XMCD signals, the researchers were able to:
- Demonstrate that the magnetic response of the iron and dysprosium sublattices is independent of the chiral domain structure.
- Reveal that the chiral domains are robust against both the structural phase transition at 280 K and the application of magnetic fields up to 4 Tesla.
- Determine that the induced magnetization is primarily contributed by the dysprosium sublattice, with the iron spins aligning mostly orthogonal to the applied field.
Insights into Orbital Hybridization and Magneto-Chiral Dichroism
The XNCD signals were found to be sensitive to the mixing of electronic orbitals in the chiral structure, providing insights into the orbital hybridization of the valence electrons. Additionally, the researchers looked for the elusive X-ray magneto-chiral dichroism (XMχD), which arises from the simultaneous breaking of parity and time-reversal symmetry. However, they were unable to detect a reliable XMχD signal, likely due to the specific magnetic configuration of the iron sublattice and the absence of a linear magnetoelectric effect in this system.
Implications and Future Outlook
The findings of this study highlight the power of X-ray spectroscopic techniques in unraveling the complex interplay between structural chirality and magnetism in materials. The insights gained into the magnetic structure and orbital hybridization of DyFe3(BO3)4 could have important implications for the development of novel spintronic and multiferroic devices. Furthermore, the absence of a detectable magneto-chiral dichroic signal underscores the challenges in observing this elusive phenomenon, guiding future research in this direction.
Author credit: This article is based on research by Daniel Haskel, Choongjae Won, Yves Joly, Jörg Strempfer, Gilberto Fabbris, Sang-Wook Cheong.
For More Related Articles Click Here
