CoFeCrGa_(1-x)Al_(x)合金的电子结构、磁性和自旋零带隙半导体特性研究

Electronic structure,magnetic properties and spin gapless semiconducting properties of CoFeCrGa_(1-x)Al_(x)

采用基于密度泛函理论(DFT)的第一性原理,研究了Al掺杂对CoFeCrGa_(1-x)Al_(x)(x=0、0.25、0.5、0.75)合金电子结构、磁性、自旋零带隙半导体特性的影响。结果表明,随着Al掺杂浓度的增加,合金晶格常数减小,总磁矩符合Slater-Pauling规则。在整个研究范围内,CoFeCrGa_(1-x)Al_(x)(x=0、0.25、0.5、0.75)合金均为自旋零带隙半导体,随着x的增加,自旋向下能带中费米面从价带顶向导带方向移动,带隙宽度逐渐增加,当x=0.75时,费米面位于带隙中间,CoFeCrAl0.75Ga0.25在系列合金中半金属稳定性最佳。此外,当受到一定程度四方形变时,CoFeCrAl0.75Ga0.25仍能保持自旋零带隙半导体特性,有望应用于自旋电子器件。

The effects of Al doping on the electronic structure,magnetic properties,and spin gapless semiconducting properties of CoFeCrGa_(1-x)Al_(x)(x=0,0.25,0.5,0.75)alloys were investigated by first-principles calculation based on density functional theory(DFT).The results show that with the increase of Al doping concentration x,the lattice constant of alloys decreases,and the total magnetic moment conforms to the Slater-Pauling rule.Within the scope of this study,CoFeCrGa_(1-x)Al_(x)(x=0,0.25,0.5,0.75)alloys are all spin gapless semiconductors.With the increase of x,the Fermi level in the spin-down energy band shifts from the top of the valence band to the conduction band,and the band gap width gradually increases.When x equals 0.75,the Fermi level is located in the middle of the band gap,and CoFeCrAl0.75Ga0.25 alloys exhibit the best half-metallicity stability in the whole series of the alloys.Moreover,CoFeCrAl0.75Ga0.25 alloys present the spin gapless semiconducting properties under certain tetragonal distortion and are expected to be a promising candidate for the spintronic devices.