Tuning of crystal structure and magnetic properties by exceptionally large epitaxial strains

Huge deformations of the crystal lattice can be achieved in materials with inherent structural instability by epitaxial straining. By coherent growth on seven different substrates the in-plane lattice constants of 50 nm thick Fe70Pd30 films are continuously varied. The maximum epitaxial strain reaches 8,3 % relative to the fcc lattice. The in-plane lattice strain results in a remarkable tetragonal distortion ranging from c/abct = 1.09 to 1.39, covering most of the Bain transformation path from fcc to bcc crystal structure. This has dramatic consequences for the magnetic key properties. Magnetometry and X-ray circular dichroism (XMCD) measurements show that Curie temperature, orbital magnetic moment, and magnetocrystalline anisotropy are tuned over broad ranges.