Magnetic Properties and the Electric Field Gradients of Fe4N and Fe4C

The magnetic properties and the hyperfine interactions of Fe4N and Fe4C under high pressures are discussed on the basis of first-principles electronic structure calculations performed by the KKR Green's function method and its extention into a full potential scheme (FP-KKR). The results show that both Fe4N and Fe4C undergo a weak first order transition from high to low spin states under pressure. This transition is sensitively reflected not only by Hhf but also by EFG. The calculated Curie temperature, magnetic moments and Hhf well reproduce the experimental observations.