Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers

Abstract

The results of combined (experimental, analytical, and micromagnetic simulations) studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems are presented. We show ways to manipulate magnetization distributions in ultrathin magnetic single or multilayers by tuning: the thickness of the magnetic layer, the thickness of either the non‐magnetic cap or spacer layer, the magnetic anisotropy, and the geometrical constrictions of the system. In ultrathin magnetic films, both the magnetization distribution and the critical thickness of the magnetization reorientation phase transition (RPT) between perpendicular and in‐plane states can be also controlled by post‐growth treatments, e.g., by either ion or light irradiation. By changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field, one can tune magnetic domain sizes in a giant range (of a few orders of magnitude) and induce the RPT. Transitions between two‐ and three‐dimensional magnetization distributions are discussed.

Modification of Magnetic Properties of Pt/Co/Pt Films by Ga+ Ion Irradiation: Focused versus Uniform Irradiation

“…Domains size (B) decreases down to few hundreds nanometers (A) while approaching the border between out-of-plane and in-plane magnetization state (SRT region). Submicrometer domain sizes near SRT were theoretically predicted in [40][41][42]. This domains behavior is consistent with the fluence gradient present across the transitional zone between the two regions that involves intermediate fluences belonging to branch 1.…”

“…As a consequence, patterning of nanoelements can be successfully achieved by uniform He + ion irradiation through masks designed by electron beam lithography [1,3]. Pt/Co ultrathin films or multilayers with perpendicular magnetic anisotropy (PMA) are the most investigated systems so far to evaluate irradiationinduced changes of magnetism [5]. For irradiation by light He + ions, structural and magnetic changes arise only from ballistic ion collisions that favor disordering and intermixing at Co-Pt interfaces.…”

Fe on W(001) from continuous films to nanoparticles: Growth and magnetic domain structure

“…One of the most interesting ferromagnetic materials is Fe because its magnetic properties are not only very sensitive to its mesoscopic and nanoscopic structure but also to its atomic structure due to the strong dependence of the exchange interaction upon interatomic distance and arrangement: Fe can be nonmagnetic or antiferromagnetic, or it can be collinear or noncollinear ferromagnetic. For this reason it has been the subject of numerous papers, mainly on fcc(001) metals, GaAs(001), W(110), and W(001) surfaces [5][6][7][8][9][10][11]. The magnetic properties have usually been probed by measuring a macroscopic response to an applied magnetic field, for example using the magneto-optic Kerr effect (MOKE) or with classical magnetometry, or after applying a magnetic field in remanence by spin-sensitive electron scattering or emission experiments.…”

Three-Dimensional Micromagnetic Simulation of Spatial Distribution of Magnetization in Thick Cobalt Layers

“…Magnetization states and magnetization processes in cobalt single layers as well as multilayers, have been intensively studied recently [1] as one of the most interesting subject of the physics of magnetism, which additionally has a huge application potential (e.g. in the engineering of high-density storage devices).…”