2024/01/15 by S W Lovesey, Lovesey, S. W.
Engineering · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Crystal Structures and Properties #FOS: Physical sciences #Magneto-Optical Properties and Applications #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2401.07637
openalex publication_date 2024/01/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The enantiomorphous (chiral) crystal class of the Sohncke-type insulator Pb(TiO)Cu4(PO4)4 permits the rotation of the plane of polarization of light (optical activity). Copper ions participate in antiferromagnetic order below a temperature 7 K, with magnetoelectric and piezomagnetic effects permitted. Lattice and magnetic symmetries of Pb(TiO)Cu4(PO4)4 are fully incorporated in calculated resonant x-ray Bragg diffraction patterns that are successfully compared with existing limited measurements on paramagnetic and magnetically ordered Pb(TiO)Cu4(PO4)4 [Misawa et al. Phys. Rev. B 103, 174409 (2021)]. Specifically, there is additional intensity in the ordered phase to a Bragg spot (a chiral signature) from circular polarization in the primary beam of x-rays. It is created by Cu axial magnetic dipoles, with the prospect of future experiments revealing interference between magnetic dipoles and charge-like (time-even, Templeton-Templeton) quadrupoles. Polar and magnetic (parity- and time-odd) Dirac quadrupoles and octupoles are potentially strong sources of diffraction when the reflection vector is parallel to the unique direction in the tetragonal lattice.