Phase transitions occurring within spatially confined regions can be useful for generating nanoscale material property modulations. Here we describe a magneto-structural phase transition in a binary alloy, where a structural transition from short-range order (SRO) to body centered cubic (bcc) results in the formation of depth-adjustable ferromagnetic layers, which reveal application-relevant magnetic properties of high saturation magnetization (M s) and low Gilbert damping (α). Here we use Fe60V40 binary alloy films which transform from initially M s = 17 kA/m (SRO structure) to 747 kA/m (bcc structure) driven by atomic displacements caused by penetrating ions. Simulations show that an estimated ∼1 displacement per atom triggers a structural transition, forming homogeneous ferromagnetic layers. The thickness of a ferromagnetic layer increases as a step-like function of the ion fluence. Microwave excitations of the ferromagnetic/non-ferromagnetic layered system reveals an α = 0.0027 ± 0.0001. The combination of nanoscale spatial confinement, low α, and high M s provides a pathway for the rapid patterning of magnetic and microwave device elements.

The ferromagnetic resonance of a disordered A2 Fe60Al40 ferromagnetic stripe, of dimensions 5 µm × 1 µm × 32 nm, has been observed in two vastly differing surroundings: in the first case, the ferromagnetic region was surrounded by ordered B2 Fe60Al40, and in the second case it was free standing, adhering only to the oxide substrate. The embedded ferromagnet possesses a periodic magnetic domain structure, which transforms to a single domain structure in the freestanding case. The two cases differ in their dynamic response, for instance, the resonance field for the uniform (k = 0) mode at ~ 14 GHz excitation displays a shift from 209 to 194 mT, respectively for the embedded and freestanding cases, with the external magnetic field applied along the long axis. The resonant behavior of a microscopic ferromagnet can thus be finely tailored via control of its near-interfacial surrounding.