Resonant x-ray scattering as a probe of toroidal moments in centrosymmetric systems

Abstract

The aim of this paper is to show that it is possible to detect, by means of resonant x-ray scattering (RXS), the magnetic toroidal moment and/or higher order time-reversal and parity-odd multipoles in centrosymmetric systems, where absorption-dichroic techniques are ineffective. We have found a material, ${\mathrm{Li}}_{2}\mathrm{V}\mathrm{O}\mathrm{Si}{\mathrm{O}}_{4}$, whose magnetic space group allows such a measurement. We then performed an ab initio numerical simulation based on a relativistic extension of the multiple scattering theory to show that the intensity of the RXS signal can be detected in modern third generation synchrotron radiation sources. Finally, we stress that RXS, unlike dichroism in absorption, allows a complete separation of toroidal dipole moment and higher order multipoles, due to the possibility of exploiting the extra degrees of freedom related to the incoming and outgoing polarizations.