Phase separated magnetic ground state in Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C

TL;DR

This study reveals that Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C, despite having long-range magnetic order, exhibits a cluster glassy ground state due to the formation of Ga-rich and Sn-rich magnetic clusters, influenced by local structural differences.

Contribution

It demonstrates the coexistence of long-range magnetic order and cluster glass behavior in a compound near a magnetostructural transition, highlighting the role of local structural variations.

Findings

Presence of long-range magnetic order in Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C.

Formation of Ga-rich and Sn-rich magnetic clusters.

Cluster size allows signatures of long-range order but limits inter-cluster interactions.

Abstract

Existence of non-ergodic ground states is considered as a precursor to a first order long range magnetostructural transformation. Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C lies compositionally between two compounds, Mn$_3$GaC and Mn$_3$SnC, undergoing first order magnetic transformation. Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C though crystallizes in single phase cubic structure, exhibits more than one long range magnetic transitions. Using a combination of magnetization, ac susceptibility, neutron diffraction and XAFS techniques it is shown that, though Mn$_3$Ga$_{0.45}$Sn$_{0.55}$C exhibits long range magnetic order, it presents a cluster glassy ground state due to formation of magnetically ordered Ga rich and Sn rich clusters. The clusters are big enough to present signatures of long range magnetic order but are distributed in such way that it limits interactions between two clusters of the same type leading to a frozen magnetic state at low temperatures. The main reason for such a cluster glass state is the difference in local structure of Mn atoms that find themselves in Ga rich and Sn rich clusters.