S. W. Lovesey

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Magnetic properties of Sohncke-type Pb(TiO)$\mathrm{C}{\mathrm{u}}_{4}{(\mathrm{P}{\mathrm{O}}_{4})}_{4}$ exposed by resonant x-ray Bragg diffraction

May 31, 2024 | link.aps.org | S. W. Lovesey |ISIS Facility |Harwell Science

The enantiomorphous (chiral) crystal class of Sohncke-type Pb(TiO)Cu4(PO4)4 permits the rotation of the plane of polarization of light (optical activity). Copper ions participate in noncollinear antiferromagnetic order below a temperature ≈ 7 K, with magnetoelectric and piezomagnetic effects permitted.
Electron orbital resonance

Dec 21, 2023 | link.aps.org | S. W. Lovesey |ISIS Facility |K. Katsumata

A magnetic resonance phenomenon is proposed, in which only the orbital degrees of freedom of electrons participate. This previously unexploited magnetic resonance may be called electron orbital resonance (EOR). To this end, a nonmagnetic, singlet ground state is necessary. In addition, the system needs to exhibit the Van Vleck paramagnetism. Conditions for EOR are met by the rare earth perovskite LaCoO3 (LCO). The D5 state of LCO is shown to exhibit the van Vleck paramagnetism that result in EOR.
Case for polar uranium octupoles in cubic ${\mathrm{U}}_{2}{\mathrm{N}}_{3}$

Dec 15, 2023 | link.aps.org | S. W. Lovesey |ISIS Facility |Harwell Science

Uranium ions in the sesquinitride α-U2N3 occupy independent acentric and centrosymmetric sites according to conventional x-ray diffraction patterns [R. Troć, J. Solid State Chem. 13, 14 (1975)]. We submit that polar uranium multipoles in acentric sites are revealed in resonant x-ray diffraction data recently published by Lawrence Bright et al. [Phys. Rev. B 100, 134426 (2019)].
Magnetic structure of ${\mathrm{RuO}}_{2}$ in view of altermagnetism

Sep 5, 2023 | link.aps.org | S. W. Lovesey |ISIS Facility |Harwell Science |D. D. Khalyavin

The magnetic structure of RuO2 and the Ru atomic configuration are unknown. A magnetic structure is inferred by confronting measured and calculated Bragg diffraction patterns and adjusting the latter to achieve satisfactory agreement. An accepted pattern, a magnetic symmetry, includes symmetry of sites occupied by the magnetic ions.
Antiferromagnetic iron-based magnetoelectric compounds

Apr 28, 2023 | link.aps.org | S. W. Lovesey |ISIS Facility |Harwell Science

Abstract The Landau free energy of a compound that benefits from a linear coupling of an electric field and a magnetic field includes a product of the two fields, one polar and time even and one axial and time odd. Evidently, the coefficient of the product of fields is unchanged by a simultaneous change in the directions of space and time, a symmetry operation labeled anti-inversion.