Abstract
The effects of pressure on the nickel hydrides with different hydrogen concentrations (, 0.25, 0.375, 0.5, 0.625, 0.6875, 0.75, and 1) have been extensively studied using the ab initio pseudopotential plane-wave method. A pressure-induced ferromagnetic (FM) to paramagnetic (PM) phase transition has been predicted. The hydrogen concentration-pressure phase diagram up to several megabar has been obtained. The transition pressure from FM to PM decreases with increasing hydrogen concentration. It is found that the electron transfers from and to inside each Ni atom and from and of Ni atoms to H are the main causes of the hydrogen-doping induced magnetic transition, while the electron transfers from the nearest-neighbor Ni to H , the nearest-neighbor Ni to the further Ni , and from to and inside each Ni atom mainly contribute to the pressure-induced magnetic transition.
- Received 11 November 2005
DOI:https://doi.org/10.1103/PhysRevB.74.052405
©2006 American Physical Society