Large magnon dichroism and other optical properties of the hexagonal ferrite <math xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mi>h</mi><mtext>−</mtext><mi mathvariant="normal">L</mi><msub><mi mathvariant="normal">u</mi><mrow><mn>0.6</mn></mrow></msub><mi mathvariant="normal">S</mi><msub><mi mathvariant="normal">c</mi><mrow><mn>0.4</mn></mrow></msub><mi>Fe</mi><msub><mi mathvariant="normal">O</mi><mn>3</mn></msub></mrow></math> with altermagnetic <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi mathvariant="normal">A</mi><mn>2</mn></msub></math> spin ordering

V. A. Martinez; A. A. Sirenko; L. Bugnon; P. Marsik; C. Bernhard; Qing Zhang; G. L. Pascut; F. Lyzwa; Z. Liu; K. Du; Xianghan Xu; S.-W. Cheong

doi:10.1103/d2sv-jvdz

Large magnon dichroism and other optical properties of the hexagonal ferrite $h − L u_{0.6} S c_{0.4} Fe O_{3}$ with altermagnetic $A_{2}$ spin ordering

V. A. Martinez ^* and A. A. Sirenko

L. Bugnon , P. Marsik , and C. Bernhard

K. Du, Xianghan Xu^†, and S.-W. Cheong

Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, USA

Department of Physics, University of Fribourg, CH-1700 Fribourg, Switzerland

School of Physics, Shandong University, Jinan 250100, China

MANSiD Research Center and Faculty of Forestry, Stefan Cel Mare University (USV), Suceava 720229, Romania

Department of Physics, New Jersey Institute of Technology, Newark, New Jersey 07102, USA and NSLS-II, Brookhaven National Laboratory, Upton, New York 11973, USA

Department of Physics, University of Illinois Chicago, Chicago, Illinois 60607–7059, USA

Keck Center for Quantum Magnetism and Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA

^*Contact author: vladimir.martinez@njit.edu
^†Present address: School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.

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Phys. Rev. B 113, 064407 – Published 5 February, 2026

DOI: https://doi.org/10.1103/d2sv-jvdz

Abstract

Multiferroic hexagonal $h − L u_{0.6} S c_{0.4} Fe O_{3}$ single crystals with noncollinear spins were studied using the THz and Raman scattering spectroscopies and ellipsometry. Antiferromagnetic resonances, or magnons, were found at about 0.85 and 1.2 THz. These magnons harden as temperature increases and disappear above 130 K. This behavior is consistent with the magnetic susceptibility and a phase transition to a previously reported weak ferromagnetic state. A strong dichroism at the resonance with the antiferromagnetic doublet has been observed at zero external magnetic field using both conventional circular polarization and THz vector vortex beams. This observation is attributed to the strong altermagnetic properties of $h − L u_{0.6} S c_{0.4} Fe O_{3}$ with broken $P$ ⋅ $T$ symmetry. The splitting of the magnon doublet in an external magnetic field applied along the $c$ axis yields a $g$ factor of 3.0 for the $F e^{3 +}$ ions. Raman spectra of the optical phonons revealed a Fano-type asymmetry due to their interaction with a continuum of polar excitations. Electronic transitions were studied with ellipsometry and the results were compared with the modeled using density functional theory combined with embedded dynamical mean-field theory.

Physical Review B

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Large magnon dichroism and other optical properties of the hexagonal ferrite $h − L u_{0.6} S c_{0.4} Fe O_{3}$ with altermagnetic $A_{2}$ spin ordering

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Large magnon dichroism and other optical properties of the hexagonal ferrite h−Lu0.6Sc0.4FeO3 with altermagnetic A2 spin ordering

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Large magnon dichroism and other optical properties of the hexagonal ferrite $h − L u_{0.6} S c_{0.4} Fe O_{3}$ with altermagnetic $A_{2}$ spin ordering