  Multiferroic composite materials, consisting of coupled ferromagnetic and
piezoelectric phases, are of great importance in the drive towards creating
faster, smaller and more energy efficient devices for information and
communications technologies. Such devices require thin ferromagnetic films with
large magnetostriction and narrow microwave resonance linewidths. Both
properties are often degraded, compared to bulk materials, due to structural
imperfections and interface effects in the thin films. We report the
development of single crystal thin films of Galfenol (Fe81Ga19) with
magnetostriction as large as the best reported values for bulk material. This
allows the magnetic anisotropy and microwave resonant frequency to be tuned by
voltage-induced strain, with a larger magnetoelectric response and a narrower
linewidth than any previously reported Galfenol thin films. The combination of
these properties make the single crystal thin films excellent candidates for
developing tunable devices for magnetic information storage, processing and
microwave communications.
