Recent advances in the Heusler based spin-gapless semiconductors

In recent years, spin-gapless semiconductors (SGSs) have received considerable interest in the fields of condensed matter physics and materials sciences due to their potential applications in novel spintronic devices. SGSs, with a zero gap at the Fermi level in one of the spin channels, can make electrons easy to excite from the valence band to the conduction band with a small input of energy and simultaneously produce electron and hole carriers with 100% spin polarization. Very recently, as a new member of SGSs family, fully-compensated ferrimagnetic spin-gapless semiconductors (FCF-SGSs) have been predicted. In addition to the properties of SGSs, FCF-SGSs possess zero magnetization, which is an added advantage for practical application. In this review article, we firstly review the progress on the Heusler-based materials with spin-gapless semiconducting behaviour, including half-Heusler compounds, full-Heusler compounds, DO3-type compounds, and LiMgPdSn-type quaternary Heusler compounds. Among these potential SGSs, some have been synthesized experimentally, while the others are just predicted by extensive first-principles calculations. Then, we explain the origin of the SGS characteristics in Heusler compounds based on the common Slater-Pauling curve and give a possible rule for making some on-demand designs of SGSs. Finally, we present a new spin injection scheme based on SGSs for practical applications and give a brief summary and outlook.