PtfeFilter phase_change Galfenol Cross-section InorganicCompound fifber oxide_layer Plug TungstenThinFilmDeposition Film Boron LiNbO3 molecular_beam temp SiWafer EPFL chemical_compound aluminum_nitride Silver Monisha Modulus frequency_modulation BismuthFerrite ForceMapping Perovskite Blend Ni81Fe19 HiVacuum Magnetic Force Microscopy Pinpoint PFM hard_disk_media Cell atomic_steps domain_switching Chrome