Temperature-Dependent Cycloidal Magnetic Structure in GdRu${}_2$Al${}_{10}$ Studied by Resonant X-ray Diffraction

Abstract

We have performed resonant X-ray diffraction experiments on the antiferromagnet GdRu${}_2$Al${}_{10}$ and have clarified that the magnetic structure in the ordered state is cycloidal with the moments lying in the $bc$ plane and propagating along the $b$ axis. The propagation vector shows a similar temperature dependence to the magnetic order parameter, which can be interpreted as being associated with the gap opening in the conduction band and the resultant change in the magnetic exchange interaction. Although the $S=7/2$ state of Gd is almost isotropic, the moments show slight preferential ordering along the $b$ axis. The $c$ axis component in the cycloid develops with decreasing temperature through a tiny transition in the ordered phase. We also show that the scattering involves the $\sigma$-${\sigma }^{\prime }$ process, which is forbidden in normal $E1$-$E1$ resonance of magnetic dipole origin. We discuss the possibility of the $E1$-$E2$ resonance originating from a toroidal moment due to the lack of inversion symmetry at the Gd site. The spin-flop transition in a magnetic field is also described in detail.

8 pages, 11 figures, accepted for publication in J. Phys. Soc. Jpn

References in corpus (5)

• Long-range order and low-energy magnetic excitations in CeRu2Al10
• The Kondo Lattice Model in Infinite Dimensions II. Static Susceptibilities and Phase Diagram
• Anisotropic spin-dynamics in the Kondo semiconductor CeRu2Al10
• A theory of the electric quadrupole contribution to resonant x-ray scattering: Application to multipole ordering phases in Ce_{1-x}La_{x}B_{6}
• Detailed neutron diffraction study of magnetic order in NdFe${}_2$Al${}_{10}$

Cited by in corpus (3)

• Helical Ordering of Spin Trimers in a Distorted Kagome Lattice of Gd${}_3$Ru${}_4$Al${}_{12}$ Studied by Resonant X-ray Diffraction
• Competition between helimagnetic and ferroquadrupolar orderings in a monoaxial chiral magnet DyNi${}_3$Ga${}_9$ studied by resonant x-ray diffraction
• A crossover from Kondo semiconductor to metallic antiferromagnet with $5d$-electron doping in CeFe${}_2$Al${}_{10}$