Distinct order of Gd 4f and Fe 3d moments coexisting in GdFe4Al8

TL;DR

This study reveals the coexistence of distinct magnetic orderings of Gd 4f and Fe 3d moments in GdFe4Al8, showing temperature-dependent transitions and incommensurate magnetic structures through comprehensive experimental characterization.

Contribution

It provides the first detailed characterization of the temperature-dependent magnetic structures and phase transitions in GdFe4Al8, highlighting the distinct ordering behaviors of Gd 4f and Fe 3d moments.

Findings

Fe moments order at TN with incommensurate modulation

Gd 4f moments order below T2 with ferromagnetic component

Gd 4f and Fe moments do not follow the same modulation at low temperatures

Abstract

Single crystals of flux-grown tetragonal GdFe4Al8 were characterized by thermodynamic, transport, and x-ray resonant magnetic scattering measurements. In addition to antiferromagnetic order at TN ~ 155 K, two low-temperature transitions at T1 ~ 21 K and T2 ~ 27 K were identified. The Fe moments order at TN with an incommensurate propagation vector (tau,tau,0) with tau varying between 0.06 and 0.14 as a function of temperature, and maintain this order over the entire T<TN range. The Gd 4f moments order below T2 with a ferromagnetic component mainly out of plane. Below T1, the ferromagnetic components are confined to the crystallographic plane. Remarkably, at low temperatures the Fe moments maintain the same modulation as at high temperatures, but the Gd 4f moments apparently do not follow this modulation. The magnetic phase diagrams for fields applied in [110] and [001] direction are presented and possible magnetic structures are discussed.