The appeal of ultra-compact spintronics drives intense research on magnetism in low-dimensional materials. Recent years have witnessed remarkable progress in engineering two-dimensional (2D) magnetism via defects, edges, adatoms, and magnetic proximity. However, intrinsic 2D ferromagnetism remained elusive until recent discovery of out-of-plane magneto-optical response in Cr-based layers, stimulating the search for 2D magnets with tunable and diverse properties. Here we employ a bottom-up approach to produce layered structures of silicene (a Si counterpart of graphene) functionalized by rare-earth atoms, ranging from the bulk down to one monolayer. We track the evolution from the antiferromagnetism of the bulk to intrinsic 2D in-plane ferromagnetism of ultrathin layers, with its characteristic dependence of the transition temperature on low magnetic fields. The emerging ferromagnetism manifests itself in the electron transport. The discovery of a class of robust 2D magnets, compatible with the mature Si technology, is instrumental for engineering new devices and understanding spin phenomena.

A class of intrinsic 2D ferromagnets – layered metalloxenes – is established by coupling graphene-like honeycomb networks of silicene and germanene with 2D lanthanide layers.

ABSTRACT:Approximate electronic trial wave function taken as the antisymmetrized product of strictly localized geminals (APSLG) is implemented for semiempirical analysis of molecular electronic structure of "organic" compounds and for calculations of their heats of formation. This resulted in an O(N)-scaling method. Using the MINDO/3 form of the semiempirical Hamiltonian with reparameterized β AB values in combination with the APSLG form of the wave function yields the computational procedure BF'98. Calculations on the heats formation and the equilibrium geometries for a wide range of molecules show that the APSLG-MINDO/3 approach is more favorable than its self-consistent field-based counterpart. Also, the APSLG formalism allows to interpret molecular electronic wave function in chemically sensible terms.

Coupling to Eu makes graphene magnetic without sacrificing its intrinsic properties.

The problem of constructing fast computational schemes has been attacked by using the antisymmetrized product of strictly localized geminals (APSLG) form of the trial wave function instead of the Slater determinant. The procedure is implemented on the semiempirical neglect of diatomic differential overlap (NDDO) level with three well-known parametrizationssmodified neglect of diatomic overlap (MNDO), first-Austin method (AM1) and third-parametric method (PM3). Heats of formation and geometry structures calculated are compared for self-consistent field (SCF) and APSLG approaches. Specific APSLG electronic structure parameterss bond characteristics and hybridization matricessobtained on the ground of variational principle are proven to correspond to chemical intuition. The advantages and limitations of the scheme proposed are discussed.