Observation of quadrupole helix chirality and its domain structure in DyFe3(BO3)4

Resonant X-ray diffraction (RXD) uses X-rays in the vicinity of a specific atomic absorption edge and is a powerful technique for studying symmetry breaking by motifs of various multipole moments, such as electric monopoles (charge), magnetic dipoles (spin) and electric quadrupoles (orbital). Using circularly polarized X-rays, this technique has been developed to verify symmetry breaking effects arising from chirality, the asymmetry of an object upon its mirroring. Chirality plays a crucial role in the emergence of functionalities such as optical rotatory power and multiferroicity. Here we apply spatially resolved RXD to reveal the helix chirality of Dy 4 f electric quadrupole orientations and its domain structure in DyFe 3 (BO 3 ) 4 , which shows a reversible phase transition into an enantiomorphic space-group pair. The present study provides evidence for a helix chiral motif of quadrupole moments developed in crystallographic helix chirality. In addition to the structural chirality of materials, there has recently been a rise in interest in the chirality arising from their magnetic and electronic structure. Using a spatially resolved resonant X-ray diffraction technique, a helical arrangement of the Dy 4 f quadrupole moments in the ferroborate system DyFe 3 (BO 3 ) 4 is uncovered.