Electronic and magnetic properties of monolayer MnS2

First-principles calculations are performed to study the electronic and magnetic properties of monolayer MnS2. Based on the electronic structure, a half-metallic state is predicted for monolayer MnS2. The magnetic moment is 3.0 [Formula: see text] per formula unit, and the main contribution is localized at the transition metal site Mn with a local moment of 3.733 [Formula: see text]. The magnetic anisotropy energy (MAE) is 0.056 meV per formula unit with an easy axis perpendicular to the plane, and it indicates that monolayer MnS2 belongs to the category of Ising magnets. The positive MAE of nanosheets mainly stems from the area around [Formula: see text] in the reciprocal space. To find the microscopic origin, we take the method of the second-order spin orbit coupling. The occupied spin-up dz2 state and the unoccupied spin-down dyz states in the [Formula: see text] point through the [Formula: see text] operator make positive contributions to the MAE.

Novel Magnetic Orders and Ice Phases in Frustrated Kondo-Lattice Models

We review recent theoretical progress in our understanding of electron-driven novel magnetic phases on frustrated lattices. Our specific focus is on Kondo-lattice or double-exchange models assuming finite magnetic moments localized at the lattice sites. A salient feature of systems with SU(2) symmetric local moments is the emergence of noncoplanar magnetic ordering driven by the conduction electrons. The complex spin textures then endow the electrons a nontrivial Berry phase, often giving rise to a topologically nontrivial electronic state. The second part of the review is devoted to the discussion of metallic spin ice systems, which are essentially frustrated Ising magnets with local spin ordering governed by the so-called ice rules. These rules are similar to those that describe proton configurations in solid water ice, hence the name "spin ice". The nontrivial spin correlations in the ice phase give rise to unusual electron transport properties in metallic spin-ice systems.