An ab-initio study of the structural, electronic and magnetic properties of half-metallic ferromagnetism in Cr-doped BeSe and BeTe

We systematically explore Cr-doped zinc blende BeSe and BeTe compounds in terms of their structural, electronic and magnetic properties by using the first-principles full-potential linearized augmented plane waves plus local orbitals (FP-LAPW + lo) method. The state stability of the doped materials has been studied by calculating the heat of formation and analysing minimum total energies in ferromagnetic (FM) and anti-ferromagnetic (AFM) coupling. A non linear dependency of Cr concentration on the lattice parameters and bulk modulus is found which shows small deviation from Vegard's law. Our calculations for each Cr concentration were performed using two different density functional theory functionals which are the Wu and Cohen (WC) and the modified Becke and Johnson local (spin) density approximation (mBJLDA). The functionals generate spin dependent band structures, electronic density of state (DOS) and magnetic moments that exhibit occurrence of half-metallic ferromagnetism which is caused by spin polarization of electron in Cr-d orbitals. Importantly, comparison between the two functionals shows that the mBJLDA functional provides a better description of the electronic structure of the Cr-doped binary systems. The calculated exchange interaction and exchange constant, N0α and N0β, respectively, are consistent with the values from typical magneto-optical experiment and conversely, the calculated charge spin densities allowed us to understand the bonding nature. In addition, the calculations of spin exchange splitting, Δx(d), exhibit important indication regarding the attractive effective potential for minority spin rather than majority spin.

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► Spin effect theoretical study on Cr-doped BeSe and BeTe has been performed using DFT.
► Better performance of mBJLDA potential is confirmed as compared to Wu–Cohen GGA.
► Half-metallic ferromagnetism in CrxBe1−xSe and CrxBe1−xTe is established.
► HM gaps for CrxBe1−xSe and CrxBe1−xTe show non-linear variation with concentration.
► Important values of exchange splitting/constants and magnetic moments are estimated.