Magnetic structure and critical behavior of GdRhIn$_{5}$: resonant x-ray diffraction and renormalization group analysis

TL;DR

This study investigates the magnetic structure and critical behavior of GdRhIn5 using resonant x-ray diffraction and renormalization group analysis, revealing a specific antiferromagnetic order and critical exponents related to phase transition.

Contribution

It provides detailed experimental and theoretical insights into the magnetic structure and critical phenomena of GdRhIn5 and related compounds, linking magnetic interactions to ground states.

Findings

GdRhIn5 exhibits a commensurate antiferromagnetic structure with tau = (0,1/2, 1/2)

Critical exponent beta = 0.35 indicates a second-order phase transition

The magnetic structure is influenced by the ratio of J1 and J2 interactions

Abstract

The magnetic structure and fluctuations of tetragonal GdRhIn5 were studied by resonant x-ray diffraction at the Gd LII and LIII edges, followed by a renormalization group analysis for this and other related Gd-based compounds, namely Gd2IrIn8 and GdIn3. These compounds are spin-only analogs of the isostructural Ce-based heavy-fermion superconductors. The ground state of GdRhIn5 shows a commensurate antiferromagnetic spin structure with propagation vector tau = (0,1/2, 1/2), corresponding to a parallel spin alignment along the a-direction and antiparallel alignment along b and c. A comparison between this magnetic structure and those of other members of the Rm(Co,Rh,Ir)n In3m+2n family (R =rare earth, n = 0, 1; m = 1, 2) indicates that, in general, tau is determined by a competition between first-(J1) and second-neighbor(J2) antiferromagnetic (AFM) interactions. While a large J1 /J2 ratio favors an antiparallel alignment along the three directions (the so-called G-AFM structure), a smaller ratio favors the magnetic structure of GdRhIn5 (C-AFM). In particular, it is inferred that the heavy-fermion superconductor CeRhIn5 is in a frontier between these two ground states, which may explain its non-collinear spiral magnetic structure. The critical behavior of GdRhIn5 close to the paramagnetic transition at TN = 39 K was also studied in detail. A typical second-order transition with the ordered magnetization critical parameter beta = 0.35 was experimentally found, and theoretically investigated by means of a renormalization group analysis.