It is known that high spin-polarization and magnetism can be found even in materials with neither transition metals nor rare earths. In this paper, we report results of the structural design, electronic structure, magnetic and optical properties of new equiatomic quaternary Heusler (EQH) KCaBX (X = S and Se) compounds. Electron exchangecorrelation interactions are described by the Wu-Cohen (WC) functional and Tran-Blaha modified Becke-Johnson exchange (mBJ) potential. Ferromagnetic ordering is stable for the cubic structure of space group F43 m in which the K, Ca, B and X atoms are located at 4c, 4d, 4a and 4b Wyckoff positions, respectively. Quaternaries at hand exhibit a perfect spin-polarization around the Fermi level, which is a result of the half-metallicity with metallic spin-up channel and semiconductor spin-dn channel. The ferromagnetic half-metallic and spin-flip band gaps are 2.648(2.470) and 0.673(0.526), respectively, for KCaBS(KCaBSe). Both studied compounds have a total magnetic moment of 2.000 μ_B. Additionally, the strain effect on the electronic and magnetic properties is also examined. Finally, the optical properties of the KCaBX alloys are investigated for energies up to 25 eV. Optical spectra show the metallic behavior at extremely low energies and semiconductor nature at higher energies. Interestingly, KCaBS and KCaBSe exhibit prospective absorption properties with a quite large absorption coefficient in the ultraviolet regime.

众所周知，即使在既没有过渡金属也没有稀土的材料中也可以发现高自旋极化和磁性。在本文中，我们报告了新型等原子四元Heusler（EQH）KCaBX（X = S和Se）化合物的结构设计，电子结构，磁和光学性质的结果。电子交换相关相互作用由Wu-Cohen（WC）功能和Tran-Blaha修饰的Becke-Johnson交换（mBJ）电势来描述。对于空间群F43 m的立方结构，其中K，Ca，B和X原子分别位于4c，4d，4a和4b Wyckoff位置，铁磁排序是稳定的。当前的四元数在费米能级附近表现出完美的自旋极化，这是由于具有金属自旋沟道和半导体自旋dn沟道的半金属性的结果。对于KCaBS（KCaBSe），铁磁半金属和自旋翻转带隙分别为2.648（2.470）和0.673（0.526）。两种研究的化合物的总磁矩均为2.000μ_乙。此外，还检查了应变对电子和磁性的影响。最后，研究了KCaBX合金的光学性能，其能量高达25 eV。光谱显示在极低能量下的金属行为，在高能量下的半导体性质。有趣的是，KCaBS和KCaBSe表现出预期的吸收特性，在紫外线条件下具有相当大的吸收系数。