Doping ofMn2VAlandMn2VSi

Abstract

Half-metallic antiferromagnets are the ideal materials for spintronic applications since their zero magnetization leads to lower stray fields and thus tiny energy losses. Starting from the Mn2VAl and Mn2VSi alloys we substitute Co and Fe for Mn and we show by means of first-principle electronic structure calculations that the resulting compounds are ferrimagnets. When the total number of valence electrons reaches the magic number of 24 the Fe-doped compounds are semi-metals and thus non-magnetic while the Co-doped ones show the desirable half-metallic antiferromagnetic character. The compounds are very likely to be synthesized experimentally since the parent compounds, Mn2VAl and Co2VAl, have been already grown in the Heusler L21 lattice structure.

Half-metallic Co-based quaternary Heusler alloys for spintronics: Defect- and pressure-induced transitions and properties

“…A 1:1:1:1 stoichiometric structure arises when one X is replaced by a more or less electronegative, transition metal element, forming a Y -type structure (F43m space group, #216) -or equiatomic quaternary HAs. [17][18][19][20][21][22][23][24][25] Neutron diffraction experiment on Co 2 MnSi show 14% of Mn sites are occupied by Co and 5-7% of Co sites by Mn. 3 Similar results were observed by EXAFS.…”

Ferrimagnetism and antiferro‐ magnetism in half‐metallic Heusler alloys

“…V and Cr impurities occupying Mn sites in ferrimagnetic Mn 2 VAl and Mn 2 VSi alloys present spin moments parallel to the Mn atoms contrary to the behavior of the Fe and Co impurities in these alloys and they lead to larger absolute values of the total spin moments [25]. Finally, rhe 24-valence electron alloys Cr 2 FeZ (Z= Si, Ge, Sn) show a region of low density of states instead of the real gap presented by the isovalent Cr 2 MnZ (Z= P, As, Sb, Bi) [22] which persists only for a very narrow range of lattice constants.…”

“…In the extreme case like Cr 2 MnSb (alloys with 24 valence electrons) Cr and Mn spin moments cancel each other and the compounds are named as fully-compensated half-metallic ferrimagnets or simply half-metallic antiferromagnets [22]. Defects in these alloys show a very interesting behavior.…”

“…When we substitute Co atoms with Cr(Mn) in the Co 2 Cr(Mn)Al and Co 2 Cr(Mn)Si compounds, the impurity atoms couple antiferromagnetically with the other transition metal atoms lowering the total spin moment [23,24]. Co and Fe impurities in Mn 2 VAl and Mn 2 VSi ferrimagnetic alloys have spin moments antiparallel to Mn and thus the total spin moment reaches closer to the zero value [25]. In this manuscript we will complete these studies presenting results for the Cr(Mn) impurites in ferromagnetic Co 2 Mn(Cr)Al and Co 2 Mn(Cr)Si alloys, the case of V and Cr impurities in ferrimagnetic Mn 2 VAl and Mn 2 VSi alloys and finally the 24-valence half-metallic antiferromagnetic alloys Cr 2 FeZ (Z= Si, Ge, Sn) using the full-potential nonorthogonal local-orbital band structure scheme (FPLO) [26].…”

“…Thus such a doping with Cr and V would have no advantages over the perfect Mn 2 VAl and Mn 2 VSi compounds for realistic applications. Cr 2 FeZ (Z=Si,Ge,Sn) alloys : Motivated by our results on the Cr 2 MnZ alloys [22], we decided to study also another family of 24-valence electrons compounds containing Fe instead of Mn: the Cr 2 FeZ alloys where Z is Si, Ge or Sn. In Fig.…”