The melilite-type compound(Sr1-x,Ax)2

Abstract

The seeking of room temperature ferromagnetic semiconductors, which take advantages of both the charge and spin degrees of freedom of electrons to realize a variety of functionalities in devices integrated with electronic, optical, and magnetic storage properties, has been a long-term goal of scientists and engineers. Here, by using the spin-polarized density functional theory calculations, we predict a new series of high temperature ferromagnetic semiconductors based on the melilite-type oxysulfide Sr 2 MnGe 2 S 6 O through hole (K) and electron (La) doping. Due to the lack of strong antiferromagnetic superexchange between Mn ions, the weak antiferromagnetic order in the parent compound Sr 2 MnGe 2 S 6 O can be suppressed easily by charge doping with either p-type or n-type carriers, giving rise to the expected ferromagnetic order. At a doping concentration of 25%, both the hole-doped and electron-doped compounds can achieve a Curie temperature (T c) above 300 K. The underlying mechanism is analyzed. Our study provides an effective approach for exploring new types of high temperature ferromagnetic semiconductors.

A family of high-temperature ferromagnetic monolayers with locked spin-dichroism-mobility anisotropy: MnNX and CrCX (X = Cl, Br, I; C = S, Se, Te)

“…In the past decades, a plenty of methods, e.g. magnetic or non-magnetic dopants [1][2][3][4][5][6][7], vacancies [8,9] and grain boundaries [10,11], have been attempted to introduce long-range ferromagnetic orders in semiconductors. The long range order is, however, limited by the dopant-host hybridization [2,12] that the highest Tc was thus recorded at ~200 K [4,[13][14][15] in Mn-doped semiconductors and the mobility remains low.…”

Synthesis of Novel Melilite-Type Iron/Cobalt Oxides and Their Oxygen Evolution Reaction Electrocatalytic Activity

“…Melilite-type compounds are described with a general formula of A 2 BC 2 X 7 and crystallize in the tetragonal system, schematically illustrated in Figure . Larger cations of alkali metals, alkaline-earth metals, and rare-earth metals are located at the A sites, − and smaller cations such as Zn, Al, Si, Ge, and TMs occupy the B and C sites. ,− The X sites contain O 2– , N 3– , and S 2– anions. − Importantly, both of the B and C sites are tetrahedrally coordinated (CN = 4), forming a two-dimensional network in the crystallographic ab -plane. The A sites are located between two blocks of the tetrahedral networks to form a layered structure.…”

Prediction of single-atom-thick transition metal nitride CrN$_4$ with a square-planar network and high-temperature ferromagnetism

“…Based on Ising model and the magnetic couplings J 1 and J 2 , we can evaluate the Curie temperature of CrN 4 monolayer. Firstly, we make a rough estimate according to the formula T c = J 1 •2/ln(1+ √ 2) when J 2 is ignored [28,37,38]. The Curie temperatures (T c1 ) are 308.5 K, 821.5 K, 944.4 K, and 1381.8 K for PBE, GGA+U, SCAN, and HSE calculations, respectively.…”