1,721,118 research outputs found
Scalar and vector hysteresis models for the description of magnetization process under alternating and rotational field
No full text
Study of metastable states in the random-field Ising model
No full textThe random-field Ising model (RFIM) provides a convenient framework to investigate complex energy landscapes.
We use an out-of-equilibrium T 1⁄4 0 single spin flip dynamics induced by varying the applied field, starting from locally
stable configurations fsi g: If the configuration considered cannot be reached by a field history from saturation, it is
possible to define a set of connected states which is defined as a basin. A whole hierarchy of basins is found when the
field is increased outside the limits of the initial basin. The resulting structure has the topology of an oriented graph. The
properties of the graph cast new light on properties of the ground state (GS) and the possibility to reach the GS by a
field history from saturation. We have numerically determined the graphs in RFIM realizations of finite size in one
dimension for arbitrary selected states and for the GS. Remarkable differences between them are found in the critical
path of the corresponding graphs, the GS being nearer to the field reachable states than a generic state
Vector magnetization processes in amorphous magnetic materials with uniaxial induced anisotropy
No full textWe report an investigation about the vector magnetization behavior of soft amorphous materials. Disk-shaped
samples, with uniaxial-induced anisotropy, were submitted to a magnetizing field Ha; oscillating along different
directions with respect to the easy axis. The measured effective field H and the magnetization display a general behavior
versus Ha; pointing out the crucial role played by the demagnetizing field. Experiments revealed two regimes in the
magnetization reversal. This phenomenology was interpreted in the framework of the N!eel phase theory applied to
uniaxial systems. We showed that the two experimental regimes correspond to magnetization modes where two or one
magnetic phases (magnetic domains) are present. We worked out the switching condition between the modes, which
involve only magnitude and orientation of the applied field. Moreover, in the two-phase mode, a simple relationship
connecting the magnetization direction to the applied field direction was found. The measured magnetization properties
are then interpreted as the combined action of domain wall motion without hysteresis and coherent rotation inside
domains. It is remarkable that agreement found is based on two parameters only: the demagnetizing coefficient and the
anisotropy field of the specimens
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