Quadrupolar Order and Structural Phase Transition in DyB4 with Geometrical Frustration

TL;DR

This study investigates the structural phase transition and quadrupolar ordering in DyB4 with geometrical frustration, revealing a transition from tetragonal to monoclinic symmetry associated with quadrupolar order below 12.7 K.

Contribution

It provides detailed experimental evidence of a lattice distortion linked to quadrupolar ordering in DyB4, highlighting a structural transition induced by geometrical frustration.

Findings

Lattice reflection splitting indicates tetragonal to monoclinic transition.

Broadening of specific reflections suggests structural distortion.

Quadrupolar ordering correlates with the observed structural phase change.

Abstract

Structural phase transition accompanying with quadrupolar ordering in DyB4 with Shastry-Sutherland type geometrical frustration has been studied by X-ray diffraction. Previous study [D. Okuyama et al.: J. Phys. Soc. Jpn. 74 (2005) 2434.] using resonant X-ray scattering revealed short-range ordering of the Ozx-type quadrupolar moments and the c-plane component of the magnetic moments in addition to long-range ordering of the c-axis component of the magnetic moments. The present report focuses on the lattice distortion below the quadrupolar ordering temperature at TN2=12.7 K. The (0 0 l=integer) fundamental lattice reflection splits into four peaks along the h and k directions and the (h=even 0 0) reflection becomes broad along the l direction. This indicates that a structural transition from tetragonal to monoclinic takes place below TN2 together with the ordering of the quadrupolar moments.