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The structural, electronic and magnetic properties of Cr, Mn, Fe, Co and Ni-doped bilayer WSe are predicted by using first principles calculations. The doped transition-metal (TM) atoms show a covalent-binding with the nearest Se atoms. The calculated electronic structures reveal that the TM Cr, Mn, Fe and Co-doped bilayer WSe exhibits a half-metallic character with a 100% spin polarization at the Fermi level, and the reason is ascribed to the strong hybridization peak between the transition metals and the parent W and Se atoms. The Ni-doped bilayer WSe is still a semiconductor with nonmagnetism. The Fe-doped system has a robust stability of half-metallicity because there are three connected states peak spanning the Fermi level. The doping of Cr, Mn, Fe and Co atoms leads to a prominent total magnetism (0.93-3.65 [Formula: see text] moment per unit cell), and an induced ∼0.3 [Formula: see text] moment in parent W atoms is found in addition to the main contribution of TM atomic magnetism (0.71-3.33 [Formula: see text] moment per atom). The predicted Cr, Mn, Fe and Co-doped bilayer WSe should be the candidate materials for spintronic devices due to their magnetic and half-metallic nature.

The electronic band structure and valley splitting of the WSe2/NiCl2 heterostructure have been investigated by density functional theory and Berry curvature calculations. We demonstrate that the valley polarization of monolayer WSe2 is induced due to the magnetic proximity effect caused by the single layer of ferromagnetic NiCl2. The magnitude of valley splitting depends on the stacking configurations of WSe2/NiCl2, and the maximum value of valley splitting reaches −11.87 meV. Large valley splitting can be achieved by adjusting the layer spacing and constructing a NiCl2/WSe2/NiCl2 heterojunction with Ni spins arranged in parallel between two NiCl2 sheets. The valley-contrasting Berry curvature between the K and K′ valleys suggests that the WSe2/NiCl2-based heterostructure could potentially be used as a valleytronic device to realize the valley-polarized anomalous Hall effect as both spin and valley filter.

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Spin splitting, valley splitting and Berry curvature at the K and K′ valleys of a MoS2/CoO(111) heterostructure can be tuned continually by biaxial tensile strain.