title: Spatial Evolution of the Ferromagnetic Phase Transition in an Exchange Graded Film.
abstract: A combination of experiments and numerical modeling was used to study the spatial evolution of the ferromagnetic phase transition in a thin film engineered to have a smooth gradient in exchange strength. Mean-field simulations predict, and experiments confirm, that a 100 nm Ni_{x}Cu_{1-x} alloy film with Ni concentration that varies by 9% as a function of depth behaves predominantly as if composed of a continuum of uncoupled ferromagnetic layers with continuously varying Curie temperatures. A mobile boundary separating ordered and disordered regions emerges as the temperature is increased. We demonstrate continuous control of the boundary position with temperature, and reversible control of the magnetization on both sides of the boundary with the magnetic field.
authors.affiliation: Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Kirby
authors.affiliation: Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
authors.forename: H F
authors.initials: HF
authors.lastname: Belliveau
authors.affiliation: Department of Physics, University of South Florida, Tampa, Florida 33620, USA.
authors.forename: D D
authors.initials: DD
authors.lastname: Belyea
authors.affiliation: Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Kienzle
authors.affiliation: Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Grutter
authors.affiliation: CIC nanoGUNE Consolider, E-20018 Donostia-San Sebastian, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Riego
authors.affiliation: CIC nanoGUNE Consolider, E-20018 Donostia-San Sebastian, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Berger
authors.affiliation: School of Chemistry and Materials Science, Rochester Institute of Technology, Rochester, New York 14623, USA.
authors.forename: Casey W
authors.initials: CW
authors.lastname: Miller