Effect of disorders on half-metallic ferromagnetism in Cr2CoAl inverse Heusler alloy

Abstract

The chromium based fully compensated ferrimagnet, Cr2CoAl has been earlier proposed to show half-metallic ferromagnetism. In this paper, we thoroughly study the effect of atomic disorders on spin polarization, half-metallic character and magnetism in Cr2CoAl using Full-Potential Linearized Augmented Plane Wave method as implemented in WIEN2k code. Cr2CoAl exists in Inverse Heusler alloy structure with space group F4¯3m (No. 216). This study includes five types of disorders namely A2a-, A2b-, DO3a-, DO3b- and B2-type (as suggested by Singh et al for Inverse Heusler alloy). Our calculations predict Cr2CoAl as near half-metallic ferromagnet with 97% spin polarization. A2a-, A2b- and DO3a-type disorders exhibit high spin polarization of 98%, 99%, and 81%, respectively, whereas DO3b-and B2- type disorder exhibit 61% and 70% spin polarization, respectively. The energetics of these disorders suggest that DO3a-type disorder is more probable to occur but the high spin polarization in spite of disorder favors its application in spintronics devices. The total spin magnetic moment of Cr2CoAl is 0 µB, which increases with the disorders.