First principles design of Ohmic spin diodes based on quaternary Heusler compounds

Abstract

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.

A VSi2P4/FeCl2 van der Waals heterostructure: a two-dimensional reconfigurable magnetic diode

“…That is to say, the Ohmic contact arises at the interface without high doping concentrations. 13,50,51…”

“…12 They further found four Ohmic contacted MTDs based on quaternary Heusler compounds, which exhibit linear I – V characteristics with zero threshold voltage. 13 However, these complicated bulk interfaces produce leakage currents and weaken Ohmic spin diode characteristics. Fortunately, the layer-by-layer control of thickness, the ultra-clean interface and the flexible stacking method of 2D vdW materials offer exciting opportunities for miniaturizing devices and exploring new physical phenomena.…”

Epitaxial Mn2VAl films with L21-ordered structure for all-Heusler stacks

“…While many theoretical studies on the electronic band structures and magnetic properties of all-Heusler stacks have been reported [19,[53][54][55][56][57][58][59][60][61][62][63][64], there has only been a few experimental studies [45,46,65,66]. In particular, for the emergence of unique physical properties expected theoretically, it is necessary to precisely control the structural ordering in not only the bulk region but also the interfacial region of all-Heusler stacks.…”

An Ab Initio Study of All‐Heusler Heterostructures: The Case of Ultrathin Multilayers

“…[33] All-Heusler structures have been proposed to have even more interesting applications like reconfigurable magnetic tunnel diodes and transistors and Ohmic spin diodes. [34][35][36][37] Li et al have proposed an all-Heusler Co 2 MnðGe 0.75 Ga 0.25 Þ=Cu 2 TiAl=Co 2 MnðGe 0.75 Ga 0.25 Þ trilayer to be used as a spin valve [38] and Yamada et al proposed a Co 2 FeSi=Fe 2 MnSi=Co 2 FeSi trilayer for high-performance current-perpendicular-to-plane giant magnetoresistive devices. [39] Motivated by the recent interest in all-Heusler multilayer (ML) heterostructures, herein a first-principles study of the structural, electronic, and magnetic properties of three systems is presented: 1) Co 2 MnSi=Co 2 FeAl ML, where both spacers are HM ferromagnetic Heusler compounds with the same total spin magnetic moment because they have the same number of valence electrons; 2) Co 2 MnAl=Mn 2 CoAl ML, where Co 2 MnAl is a ferromagnetic half-metallic Heusler compound and Mn 2 CoAl is an SGS material; and 3) Co 2 TiAl/(CoV)TiAl ML, where Co 2 TiAl is an HM ferromagnetic Heusler compound and (CoV)TiAl an SFM Heusler.…”