Two-dimensional hexagonal manganese carbide monolayer with intrinsic ferromagnetism and half-metallicity

Abstract

Recent experimentally observed intrinsic ferromagnetism in two-dimensional (2D) van der Waals crystals has ignited substantial interests due to their great potential in spintronic devices. However, their practical applications are hampered by rather low Curie temperature and small magnetic anisotropic energy. Here, we predict from first-principles calculations that the 2D pristine hexagonal manganese carbide (h-MnC) sheet exhibits robust ferromagnetic and half-metallic features with complete spin polarization, sizable magnetic anisotropic energy, and wide half-metallic gap near the Fermi energy level. Moreover, the h-MnC sheet can retain its structure up to the temperature of 1000 K, indicating a highly thermodynamic stability. The Monte Carlo simulations based on the Heisenberg model with single-ion anisotropy predict a Curie temperature of 233 K in 2D h-MnC crystal. We confirm the robustness of the ferromagnetism and half-metallicity against the external strain from −6% to 10%. Also, a feasible experimental fabrication route is proposed to realize the h-MnC monolayer via heterostructure engineering and exfoliation techniques. Overall, the robustness of the half-metallicity in combination with the high-temperature ferromagnetism render the freestanding h-MnC monolayer and even its energetically favorable h-MnC/MoS2 and h-MnC/MoSe2 heterostructures quite promising materials for developing practical spintronic nanodevices.

Identification of a Magnetic Phase via a Raman Spectrum in Single-Layer MnSe: An ab Initio Study

“…Apparently, the soft nature of the MnSe phases can be seen through the Poisson ratio values which are found to be over 0.64. While they are much larger than those reported for graphene (0.19) and MoS 2 (0.26), they are smaller than those for the predicted single layers of MnC (0.94) and MnN (0.87) . Relatively large Poisson ratios of MnSe phases reveal the strong ability of the structure to preserve its equilibrium state under external applied strain.…”

“…On the other hand, varying values (21–26 N/m) of the in-plane stiffness in single-layer MnSe indicate the soft nature of the all magnetic phases mechanically. As compared to the predicted 2D Mn-based single-layer materials, such as hexagonal MnC (6 N/m) and MnN (10 N/m), single-layer MnSe is relatively stiffer; however, it is softer than well-known 2D structures of few-atom thick TMDs such as MoS 2 (122 N/m) . Similarly, the orientation-dependent Poisson ratio is calculated using eq , and the values for the two main orientations, ν zz and ν ac , are listed in Table .…”

Two-dimensional ferromagnetic semiconductors of rare-earth Janus 2H-GdIBr monolayers with large valley polarization

“…A high T c is crucial for the practical application of spintronic devices. To determine the long-range magnetic exchange interactions of the Janus 2H-GdIBr monolayer, the metropolis Monte Carlo algorithm based on the Heisenberg model is used, and the spin Hamiltonian can be described as 52 where S i and S j are the spin operators, J represents the isotropic part of exchange interaction, and D represents the single-ion magnetic anisotropy on iron. All parameters in eqn.…”

Monolayer gadolinium halides, GdX2 (X = F, Cl, Br): intrinsic ferrovalley materials with spontaneous spin and valley polarizations

“…Apart from the sizable MAE values against the heat fluctuation, the FM materials should have high Curie temperatures ( T C ) comparable to or above room temperature, which is very pivotal for practical applications in spintronic devices. 57 To estimate the T C of MLs GdX 2 , we have launched a series of MC simulations based on the classical Heisenberg model, 34,36,51,58 where the Hamiltonian can be expressed aswhere J is the magnetic exchange parameter between two nearest-neighboring i and j Gd-sites, A is the single-site magnetic anisotropy parameter, and S z i refers to the z -component of spin vector S i of the i th Gd-site. Both J and A are derived from the mapping analysis of various spin configurationswhere E FM , E AFM , and E 0 are the total energies of the FM, AFM, and nonmagnetic states as shown in Fig.…”