Heterogeneous magnetism and kinetic arrest in antiperovskite Mn sub(3-x) Ni sub(x) GaC compounds with Ni sub(2) MnGa Heusler insertions

Abstract

Mn-based antiperovskite compounds in the form Mn sub(3) AX, where A is a main group element and X is C or N, undergo magnetostructural transitions with which these materials acquire magnetocaloric, giant magnetoresistance, and spin-transport properties, which can be modified or tailored by manipulating the compositions of numerous compounds. This enables closer investigations and better understandings of the underlying principles governing these properties. Mn sub(3-x) Ni sub(x) GaC, which is a derivative of the prototype Mn sub(3) GaC antiperovskite, would normally be expected to form a cubic structure with a homogeneous composition. Contrary to this, we find that the addition of Ni leads to a heterogenous compound consisting of an antiperovskite part and a Ni sub(2) MnGa Heusler insertions. The system shows kinetic arrest features, which we study as a function of Ni composition using the techniques of x-ray diffraction, magnetization, and neutron diffraction under a magnetic field.