First-principles study of charging effect on magnetism of Pd (100) ultrathin films

Calculations of electronic structure of free-standing Pd (100) ultrathin films of 2-6 monolayers (MLs), using first-principles calculation with pseudopotential method, show stable ferromagnetism in 4 ML and induced magnetic phase transition in 3 and 4 MLs by charging. The ferromagnetism, appearing due to large density of states attributed to 4d(xz,yz) flat bands at Fermi energy epsilon(F), can be manipulated by charging through the change in the contribution of the 4d flat bands to epsilon(F), where the surface carrier density of >10(13) cm(-2) is necessary for the magnetic phase transition. This can be experimentally realized using techniques such as electric double layer transistors. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4757409]