Spin Gapless Semiconductor-Nonmagnetic Semiconductor Transitions in Fe-Doped Ti\({}_{2}\)CoSi: First-Principle Calculations  
[PERSON]  
1 School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China; [EMAIL_ADDRESS] (Y.F.); [EMAIL_ADDRESS] (Z.C.); [EMAIL_ADDRESS] (M.-s.W.) 1  
[PERSON]  
1 School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China; [EMAIL_ADDRESS] (Y.F.); [EMAIL_ADDRESS] (Z.C.); [EMAIL_ADDRESS] (M.-s.W.) 1  
[PERSON]  
1 School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China; [EMAIL_ADDRESS] (Z.C.); [EMAIL_ADDRESS] (M.-s.W.) 1  
[PERSON]  
2 School of Physics and Electronic Science, Zunyi Normal University, Zunyi 563002, China;  
3 School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China 23 Department of Physics, The University of Lahore, Sargodha Campus, Sargodha 40100, Pakistan; [EMAIL_ADDRESS] 3  
[PERSON]  
4 Correspondence: [EMAIL_ADDRESS]; Tel.: +86-0851-2892-715344  
semiconductors, such as MgO and GaAs. They are, therefore, regarded as one of the most excellent candidates for electrode materials of spintronics devices, such as magnetic tunnel junctions (MTJ) and current-perpendicular-to-plane spin valves (CPP-SV), and have a great application potential in magnetic random access memory (MRAM), ultra-high-speed reading in magnetic read heads of hard disk drivers (HDD) and spin transfer torque (STT) devices in spin random access memory [14; 15; 16; 17; 18; 19; 20; 21]. In addition, a lot of Heusler compounds, especially half-Heusler compounds with chemical formula of XYZ, exhibit semiconductor character. Owing to high Seebeck coefficient, large electrical conductivity, good thermal stability, and environmentally friendly constituents, semiconducting Heusler compounds, such as \(n\)-type MnNiSn (M = Ti, Zr, Hf) and \(p\)-type ErNiSn, HfPtSn, became promising thermoelectric materials which could recycle waste heat into electricity [22; 23; 24; 25]. Hence, they are great useful for wearable devices like smart watches, and for sensors in industrial process monitoring. More recently, much attention has been paid to a new subfamily of Heusler compounds which were characterized with a novel band structure, that there is an energy gap that lies in minority bands, while the valence and conduction band edges of the majority of electrons touch at Fermi level, resulting in a zero-width gap. They are, therefore, classified to be spin gapless semiconductors (SGSs) [26]. Heusler compound Mn\({}_{2}\)CoAl with SGS properties has been successfully fabricated, and high Curie temperature (T\({}_{\text{C}}\)) of 720 K as well as magnetism of 2 \(\mu_{\text{B}}\) were detected [27; 28; 29]. Others, like Ti\({}_{2}\)CoSi and CoFeCrGa, also received intense research interest [30; 31; 32; 33; 34]. Owing to the extraordinary band structure, both electrons and holes of SGS Heusler compounds can be spin-polarized, and almost no threshold energy is required to move electrons from the valence band to the conduction band, as the mobility of carriers is stronger than that in regular semiconductors. Hence, they are considered to be possible candidates to substitute for diluted magnetic semiconductors (DMS) [35]. Due to the reason that diverse valence electrons configurations of Heusler compounds result in varied magnetic properties and electronic structures, in this paper, we studied the influence of impurity Fe atom on magnetism and electronic structures of Heusler compound Ti\({}_{2}\)CoSi.