We
compile a large data set designed for the efficient benchmarking
of exchange–correlation functionals for the calculation of
electronic band gaps. The data set comprises information on the experimental
structure and band gap of 472 nonmagnetic materials and includes a
diverse group of covalent-, ionic-, and van der Waals-bonded solids.
We used it to benchmark 12 functionals, ranging from standard local
and semilocal functionals, passing through meta-generalized-gradient
approximations, and several hybrids. We included both general purpose
functionals, like the Perdew–Burke–Ernzerhof approximation,
and functionals specifically crafted for the determination of band
gaps. The comparison of experimental and theoretical band gaps shows
that the modified Becke–Johnson is at the moment the best available
density functional, closely followed by the Heyd–Scuseria–Ernzerhof
screened hybrid from 2006 and the high-local-exchange generalized-gradient
approximation.
Reconfigurable magnetic tunnel diodes and transistors are a new concept in spintronics. The realization of such a device requires the use of materials with unique spin-dependent electronic properties such as half-metallic magnets (HMMs) and spin-gapless semiconductors (SGSs). Quaternary Heusler compounds offer a unique platform to design within the same family of compounds HMMs and SGSs with similar lattice constants to make coherent growth of the consecutive spacers of the device possible. Employing state-of-the-art first-principles calculations, we scan the quaternary Heusler compounds and identify suitable candidates for these spintronic devices combining the desirable properties: (i) HMMs with sizable energy gap or SGSs with spin gaps both below and above the Fermi level, (ii) high Curie temperature, (iii) convex hull energy distance less than 0.20 eV, and (iv) negative formation energies. Our results pave the way for the experimental realization of the proposed magnetic tunnel diodes and transistors. arXiv:2001.07029v1 [cond-mat.mtrl-sci] In the main text we discuss electronic and magnetic properties of in total 25 half-metallic magnets (HMMs) and spin-gapless semiconductors (SGSs) for realization of reconfigurable spintronic devices. In this supplementary part we provide the total density of states (DOS) for all 25 compounds. S1 arXiv:2001.07029v1 [cond-mat.mtrl-sci]
The Ohmic spin diode (OSD) is a recent concept in spintronics, which is based on half-metallic magnets and spin-gapless semiconductors (SGSs). Quaternary Heusler compounds offer a unique platform to realize the OSD for room temperature applications as these materials possess very high Curie temperatures as well as half-metallic and spin-gapless semiconducting behavior within the same family. Using state-of-the-art first-principles calculations combined with the nonequilibrium Green's function method, we design four different OSDs based on half-metallic and spin-gapless semiconducting quaternary Heusler compounds. All four OSDs exhibit linear current–voltage (I–V) characteristics with zero threshold voltage VT. We show that these OSDs possess a small leakage current, which stems from the overlap of the conduction and valence band edges of opposite spin channels around the Fermi level in the SGS electrodes. The obtained on/off current ratios vary between 30 and 105. Our results can pave the way for the experimental fabrication of the OSDs within the family of ordered quaternary Heusler compounds.
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