Half‐Metallicity in Quaternary Heusler Alloys with 3d and 4d Elements: Observations and Insights from DFT Calculations

Abstract

In this work, important insights into the evolution of half‐metallicity in quaternary Heusler alloys are provided. Employing ab initio electronic structure methods we study 18 quaternary Heusler compounds having the chemical formula CoX′Y′Al, where Y′ = Mn, Fe; and X′ a 4d element. Along with the search for new materials for spintronics applications, the trends in structural, electronic, magnetic properties, and Curie temperature are investigated. Comparative studies with the compounds in the quaternary series CoX′Y′Si with X′ materials from the 3d and 4d transition metal series in the periodic table have been made. We observe that the half‐metallic behavior depends primarily on the crystal structure type based on atomic arrangements and the number of valence electrons. As long as these two are identical, the electronic structures and the magnetic exchange interactions bear close resemblances. Consequently, the materials exhibit identical electronic properties, by and large. The roles of different transition metal atoms in affecting the hybridizations and their correlations with the above observations are analyzed. This work, therefore, provides important perspectives regarding the underlying physics of half‐metallic behavior in quaternary Heusler compounds which goes beyond specifics of a given material. This, thus, paves the way for smart prediction of new half‐metals. This work also figures out an open problem of understanding how different ternary Heuslers with different electronic behavior may lead to half‐metallic behavior in quaternary Heuslers with 4d transition metal elements.

Pressure dependent half-metallic ferromagnetism in inverse Heusler alloy Fe2CoAl: a DFT+U calculations

“…76 This result also agrees well with the results for several other analogous Fe-based inverse Heusler alloys whose lattice parameters vary from 5.5 to 6.2Å. 35,54,55,[77][78][79][80][81][82][83][84] Further, the cohesive energy has been calculated from eqn (1). The cohesive energy results are presented in Fig.…”

Tuning the electronic and magnetic properties of CoZrxNb1−xFeSi alloys for spintronic and thermoelectric applications

“…Ghosh et al [4] showed that CoZrFeSi is a ferromagnet half metal with 100% spin polarization; however, CoNbFeSi is near half metal. Also, another recent study has confirmed this by investigating a collection of quaternary Heusler alloys with CoX′Y′Al formula where Y′ = Mn, Fe and X′ is a 4d element [3].…”

“…Quaternary Heusler alloys are an interesting family to investigate as they have important magnetic and transport characteristics [1]. They are specifically promising for spintronics and magneto‐electronic and thermoelectric applications [2, 3]. The most studied quaternary Heusler alloys have their magnetic properties from the 3d transition metals (TM).…”

“…The main reason for the half metallicity character of these alloys is the hybridization of the unfilled 3d shells. Thus, the quaternary Heusler compounds containing 4d transition metals can lead to new avenues in finding new compounds for spintronics [2–4]. The CoRuFeX (X = Si, Ge) properties were considered [2].…”

Characterization of quaternary Heusler alloys CoFeYGe ( Y = Ti, Cr) with respect to structural, electronic, magnetic, mechanical, and thermoelectric features

“…16,17 Based on the various atom orientations, there are three potential configurations for this structural type. 18,19 Although some of these transition metals have been discovered to have typical ferromagnetism, it is likely that some of the X, X 0 , and Y elements are 3d transition metals with a partial halfmetallicity property that leads them to become unstable when subjected to strain. As a result, further research was carried out, this time focusing on 4d transition chemicals.…”