Fully understanding the properties of n-type ferromagnetic semiconductors (FMSs), complementary to the mainstream p-type ones, is a challenging goal in semiconductor spintronics because ferromagnetism in n-type FMSs is theoretically nontrivial. Soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) is a powerful approach to examine the mechanism of carrier-induced ferromagnetism in FMSs. Here our SX-ARPES study on the prototypical n-type FMS (In,Fe)As reveals the entire band structure, including the Fe-3d impurity bands (IBs) and the host InAs ones, and provides direct evidence for electron occupation of the InAs-derived conduction band (CB). A minority-spin Fe-3d IB is found to be located just below the conduction-band minimum (CBM). The IB is formed by the hybridization of the unoccupied Fe 3d states with the occupied CBM of InAs in a spin-dependent way, resulting in the large spin polarization of CB. The band structure with the IB is varied with band filling, which cannot be explained by the rigid-band picture, suggesting a unified picture for realization of carrier-induced ferromagnetism in FMS materials.

Low cost and highly efficient two dimensional materials as photocatalysts are gaining much attention to utilize solar energy for water splitting and produce hydrogen fuel as an alternative to deal with the energy crisis and reduce environmental hazards.

The aim of this paper is to characterize left almost rings by congruence relations. We show that each homomorphism of left almost rings defines a congruence relation on left almost rings. We then discuss quotient left almost rings. At the end we prove analogue of the isomorphism theorems for left almost rings.

The construction of van der Waals heterostructures are extensively studied for designing new devices for potential applications in nanotechnology and renewable energy. In this work, we perform the first-principles calculations...