Magnetic behavior of Gd3Ru4Al12, a layered compound with a distorted Kagome net

TL;DR

This study investigates the magnetic properties of Gd3Ru4Al12, revealing long-range antiferromagnetic order, precursor ferromagnetic clusters, and geometric frustration effects through magnetization, heat capacity, and magnetoresistance measurements.

Contribution

It provides the first detailed experimental analysis of Gd3Ru4Al12's magnetic behavior, highlighting the coexistence of frustration, precursor ferromagnetic clusters, and long-range antiferromagnetic order.

Findings

Long-range antiferromagnetic order below 18.5 K

Presence of ferromagnetic clusters above TN

Evidence of geometric frustration effects

Abstract

The magnetic behavior of the compound, Gd3Ru4Al12, which has been reported to crystallize in a hexagonal structure about two decades ago, had not been investigated in the past literature despite interesting structural features (that is, magnetic layers and triangles as well as Kagome-lattice features favouring frustrated magnetism) characterizing this compound. We report here the results of magnetization, heat-capacity, and magnetoresistance studies in the temperature (T) range 1.8-300 K. The results establish that there is a long-range magnetic order of an antiferromagnetic type below (TN= ) 18.5 K, despite a much large value (about 80 K) of paramagnetic Curie temperature with a positive sign characteristic of ferromagnetic interaction. We attribute this to geometric frustration. The most interesting finding is that there is an additional magnetic anomaly below about 55 K before the onset of long range order in the magnetic susceptibility data. Concurrent with this observation, the sign of isothermal entropy change remains positive above TN with a broad peak above TN. This observation indicates the presence of ferromagnetic clusters before the onset of long range magnetic order. Thus, this compound may serve as an example for a situation in which magnetic frustration due to geometrical reasons is faced by competition with such precursor effects. There is also a reversal of the sign of entropy-change in the curves for lower final fields (for H less than 30 kOe) on entering into magnetically ordered state consistent with the entrance into antiferromagnetic state. The magnetoresistance behavior is consistent with above conclusions.