Molecular beam epitaxy of Pd-Fe graded alloy films for standing spin waves control

This study demonstrates capabilities of a molecular beam epitaxy method for the deposition of ferromagnetic Pd–Fe alloy thin films with variable compositions across film thickness. It is proposed as a technological route to synthesize graded magnetic materials possessing unusual physical properties. A particular approach to realize a concentration profile through temperature control of an effusion cell during deposition is described in detail. Using this technique, graded ferromagnetic films were synthesized and characterized to reveal the possibility of controlling the spectrum of standing spin waves in them. Limitations of creating Pd–Fe films magnetically profiled across the thickness are discussed, associated with the thermal inertia of effusion cells and possible phase separation.