First-Principles Study of Carrier-Mediated and Vacancy-Induced Ferromagnetism in Molybdenum Disulfide Monolayer

We have investigated the magnetic properties of semiconducting molybdenum disulfide (MoS2) monolayer (ML) using the plane wave self-consistent field (PWscf) method within the framework of density functional theory (DFT). The pristine semiconducting bulk MoS2 is nonmagnetic (NM), due to the spin pairing of two electrons. We have indicated that the carrier-mediated ferromagnetism is available on the MoS2 ML as both the hole and electron carriers. The ordinary neutral S (VS0) vacancy creates the localized vacancy defect level and this level does not create the ferromagnetic (FM) state due to the spin pairing of two electrons by three Mo dangling bonds. While we have shown that the FM state is possible to create the FM state, due to the additional hole and electron carriers on the valency band and localized vacancy defect level by positively and negatively charged S (VS1+ and VS1- ) and positively charged Mo (VMo1+) vacancies.

Preparation and Properties of Gallium Phosphide Doped by Rare-Earth Elements

ABSTRACTGaP single crystals have been grown from 5at.% solution of P in Ga with (0.01-0.1)at.% of La, Sm or Gd as dopants. Electric properties, photoconductivity and luminescence of the crystals have been investigated by standard methods.Energy levels of impurities, mobility and concentration of current carriers have been determined in wide temperature region. It was shown that nitrogen (N) and other uncontrolled impurities present in the crystals due to some peculiarities of crystal growth. The intrinsic RE impurity luminescent spectra can be seen only together with spectra of excitons bounded on N traps. The evaluation of quantum eficiency for RE impurity made on the base of luminescence decay measurements gives the value close to 1. The interpretation of GaP:RE luminescence spectra is presented as intrashell transitions activated by bound exciton recombination as well as D-A and D-valency band transitions between some contaminating impurity (donor) and RE element (acceptor).