First-principles computational exploration of ferromagnetism in monolayer GaS via substitutional doping

Abstract

Using first-principles calculations, functionalization of the monolayer-GaS crystal structure through N or Cr-doping at all possible lattice sites has been investigated. Our results show that pristine monolayer-GaS is an indirect-bandgap, non-magnetic semiconductor. The bandgap can be tuned and a magnetic moment (MM) can be induced by the introduction of N or Cr atomic anion/cation doping in monolayer GaS. For instance, the intrinsic character of monolayer GaS can be changed by substitution of N for the S-site to p-type, while substitution of Cr at the S-site or Ga-site induces half-metallicity at sufficiently high concentrations. The defect states are located in the electronic bandgap region of the GaS monolayer. These findings help to extend the application of monolayer-GaS structures in nano-electronics and spintronics. Since the S-sites at the surface are more easily accessible to doping in experiment, we chose the S-site for further investigations. Finally, we perform calculations with ferromagnetic (FM) and antiferromagnetic (AFM) alignment of the MMs at the dopants. For pairs of impurities of the same species at low concentrations we find Cr atoms to prefer the FM state, while N atoms prefer the AFM state, both for impurities on opposite surfaces of the GaS monolayer and for impurities sharing a common Ga neighbor sitting at the same surface. Extending our study to higher concentrations of Cr atoms, we find that clusters of four Cr atoms prefer AFM coupling, whereas the FM coupling is retained for Cr atoms at larger distance arranged on a honeycomb lattice. For the latter arrangement, we estimate the FM Curie temperature T C to be 241 K. We conclude that the Cr-doped monolayer-GaS crystal structure offers enhanced electronic and magnetic properties and is an appealing candidate for spintronic devices operating close to room temperature.

Exploring the Properties of Zr2CO2/GaS Van der Waals Heterostructures for Optoelectronic Applications

“…and Figure SI4(a-c). Table I indicates that at the optimal lattice constant the bandgap for GaS (Zr 2 CO 2 ) monolayer increased to 3.49 eV (2.78 eV) consistent with previous works [18,45].…”

Room Temperature Ferromagnetism in Hydrogenated Janus CrSSe Monolayer Using Quantum Monte Carlo Simulation

“…Unfortunately, most of the two materials are non-magnetic semiconductors, but for spintronic applications, we need ferromagnetic (FM) and antiferromagnetic (AFM) semiconductors, and second, the materials must have a large spin polarization at the Fermi energy level. We can achieve the FM/AFM order only by external field and functionalization as reported in previous work. − Therefore, it is very important to promote the practical applications of pure non-magnetic semiconductors. To make them magnetic either through impurity atoms or intrinsic defects is suggested.…”

The effect of substitutional doping of Yb2+ on structural, electronic, and optical properties of CsCaX 3 (X: Cl, Br, I) phosphors: a first-principles study

“…The previously reported theoretical and experimental values of these parameters are given within parentheses. In general, the most effective method for substitutional doping is to replace partially a cation at the cation site and an anion at the anion-site to induce impurity state(s) within the bandgap of pristine materials [16]. For this, we chose Yb +2 for substitutional doping at all possible sites in pristine CsCaCl 3 .…”

“…The optimized lattice constant for Yb +2 doped CsCaCl 3 at concentration levels of 5% and 10% is 5.45 Å and 5.46 Å, respectively, which is slightly elongated from the equilibrium lattice constant of pristine CsCaCl 3 . The elongation from the equilibrium lattice constant increases the thermal stability of the material [16,31]. So at higher dopant concentrations, the substitution of Ca atom with Yb +2 would induce slight local structure distortions.…”

“…Based on the previously mentioned reason we believe that the study of Yb 2+ doped with various concentrations in CsCaX 3 (X: Cl, Br, I) needs further investigation. To improve the electronic and optical properties of CsCaX 3 (X: Cl, Br, I) the substitutional doping of cation at a cation site and anion at an anion site is an effective technique [16]. By varying the dopant concentrations, the desired results can be achieved and a more efficient inorganic phosphor material can be found for various applications.…”