Curie temperature of body-centered-tetragonal Ni

Abstract Body-centered-cubic (bcc) Ni, which does not exist in nature, has recently been achieved as a thin film on GaAs (0 0 1) via molecular beam epitaxy. Its Curie temperature ( T c ) is determined to be 456 K, much lower than that of face-centered-cubic (fcc) Ni (627 K). In order to understand how T c depends on the lattice structure, we have conducted a systematic study on the Curie temperature as a function of the tetragonal distortion ( c / a ) , i.e., the gradual transformation from bcc-Ni ( c / a = 1 ) to fcc-Ni ( c / a = 1.414 ) , using the self-consistent all electron linearized augmented plane-wave (LAPW) method in the local spin-density approximation (LSDA) together with the Monte Carlo (MC) simulations. The result shows that T c does increase monotonously about 180 K as the c / a ratio changes from bcc to fcc-Ni, which clearly explains and confirms the experimental observations.