Temperature-controlled interlayer exchange coupling in strong/weak ferromagnetic multilayers: A thermomagnetic Curie switch

Structural transformations among austenite, ferrite and cementite in Fe–C alloys: A unified theory based on ab initio simulations

“…First, since the exchange parameter J of FM bcc Fe ($0.2 eV) is much larger than that of PM fcc Fe (close to 0) [46], the Fe atoms at the interface between PM austenite and FM ferrite are more strongly coupled to the FM ferrite side, and thus more likely to follow the FM ordering, known as the magnetic proximity effect [47][48][49]. This is also supported by a recent work from Razumov et al [50], which reported that the short-range FM ordering in PM austenite is essential for the martensitic transformation of the Fe lattice.…”

Magnetocaloric effect in ferromagnet/paramagnet multilayer structures

“…The temperature dependence of the exchange coupling between the fer romagnetic layers in such a system has been studied both theoretically and experimentally [7][8][9]. Thin films of Ni x Cu 1 -x alloys were used as "weak" ferro magnetic spacers.…”

Spatial Evolution of the Ferromagnetic Phase Transition in an Exchange Graded Film

“…To explore the case of an exchange strength gradient, we chose nickel-copper alloy as a model system, because it forms isomorphous solid solutions, and it exhibits T C that changes linearly with composition. [11,12] By varying the nickel content during growth, a rational distribution of J (and thus T ′ C ) can be achieved in films with well controlled depth (z) dependent composition, e.g., Ni x(z) Cu 1−x(z) . of their respective T C .…”

“…[27] Further, since the volume of ferromagnetically ordered spins changes with temperature in these structures, one can envision novel application in thermomagnetic sensors and switches. [12] For instance, a symmetrically graded structure with the paramagnetic region in the center could show complex temperature dependent magnetic coupling, since the thickness of the paramagnetic interlayer region will be temperature dependent. In addition, rationally designed composition profiles could be employed to achieve specifically desired temperature and field dependencies.…”