Disorder Induced Magnetic Behavior of Non-Stoichiometric Co0.75Mn0.5Fe0.75Si Full-Heusler Alloy

Abstract

Many stoichiometric Heusler alloys have been extensively investigated in recent years due to their wide range of magnetic properties. However, a lack of investigation has been found for non-stoichiometric Heusler alloys. This report endeavored to grow few non-stoichiometric compositions but only succeeded in growing Co0.75Mn0.5Fe0.75Si composition. It is crystallized in LiMgPdSn prototype (space group-F43m) structure having lattice parameter of 5.66 Å, and transmission electron microscopy reveals a single phase of Co0.75Mn0.5Fe0.75Si quaternary Heusler alloy. Magnetization variation with applied magnetic field reveals slightly deviated from the magnetic moments (~ 3.53–3.70 μ B/ f. u.) of stoichiometric CoFeMnSi alloys. Interestingly, the magnetic moment of Co0.75Mn0.5Fe0.75Si is found to be 3.80 μ B/ f. u. at room temperature, which is greater than the magnetic moments (3.44 μ B/ f. u.) at 5 K temperature. Moreover, a significant splitting between zero-field cooled (ZFC) and field cooled (FC) curve points towards the co-existence of the ferromagnetic (FM) and antiferromagnetic (AFM) state in the Co0.75Mn0.5Fe0.75Si sample, which is associated due to disorder present in a cubic structure. Thus, the presence of exchange biasing associated with the FM and AFM eventually shows extreme importance in magneto-resistive device and sensors, which is not evidenced in stoichiometric Heusler alloys. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.