Magnetic structure and fluctuations ofGd2IrIn8:A resonant x-ray diffraction study

Abstract

Resonant x-ray diffraction measurements on Gd 2 IrIn 8 reveal an antiferromagnetic structure below T N ϭ40.8 K with wave vector ϭ(1 2 ,0,0) and the Gd moments lying in the tetragonal ab plane, indicating partly frustrated exchange interactions. Strong ͑over three orders of magnitude͒ dipolar resonant enhancements of the magnetic reflections were observed at both Gd L II and L III edges, indicating a relatively high magnetic polarization of the Gd 5d levels. Three-dimensional magnetic fluctuations are evidenced below T N , while measurements taken slightly above T N are consistent with two coexisting length scales for the magnetic correlations. Implications of these results for the physics of Ce n M m In 3nϩ2m (M ϭCo, Rh, or Ir͒ heavy-fermion superconductors are discussed.

Distinct order of Gd4fand Fe3dmoments coexisting inGdFeAngst1, Kreyßig2, Janssen3 et al. 2005Phys. Rev. B9020View full textAdd to dashboardCite

“…For this situation, a very weak intensity of the corresponding magnetic satellites is expected. 28 Compared to other Gd compounds, 29,30,31,32 the intensity of the satellite reflections we observed is indeed very weak − more than three orders of magnitude lower. This low intensity might be due to the ordered moments pointing into a direction close to [001], since in our scattering geometry we are not sensitive to moments in [001] direction.…”

“…34,35,36,37,38), compared to the substantial enhancements often observed at rare earth L edges (see for example Refs. 29,30,31,32).…”

Magnetic structure and critical behavior ofGdRhIn5: Resonant x-ray diffraction and renormalization group analysis

“…However, while the magnetic intensities tends to zero as T ∼ T N for GdRhIn 5 , a significant residual scattering was observed near and above the transition for Gd 2 IrIn 8 , which may be mostly ascribed to magnetic correlations in the near surface region due to long-range correlated quenched disorder. 22,41 This effect smooths out the transition observed by x-ray diffraction, and interfere severely in the extraction of the β critical exponent. We conclude that, although both compounds were equally finely polished before measurements, our studied Gd 2 IrIn 8 surface showed a larger degree of near-surface disorder, leading to a less reliable extraction of the β exponent.…”

“…4(b), where the critical behavior of Gd 2 IrIn 8 , using data of ref. 22 , is directly compared to GdRhIn 5 . In the ordered phase (T < T N ), both compounds appear to show identical behavior, described by the same critical exponent β ∼ 0.35.…”

“…22 A theoretical renormalization group analysis was performed. Our results suggest that spin anisotropy terms, possibly arising from dipolar and other fairly weak interactions, must be claimed to understand the second order of the paramagnetic transition of GdRhIn 5 and the related compound Gd 2 IrIn 8 .…”