Local magnetization profile and geometry magnetization effects in microwires as determined by magneto-optical Kerr effect

摘要

The local magnetization profile along the length in magnetostrictive Fe-based magnetic microwires has been determined by magneto-optical Kerr effect. The study has been performed in microwires with different geometrical dimensions (i.e., diameter and length). The profiles of remanent magnetization and coercivity remain constant at the middle part for all microwires, whereas significant reduction of net magnetization accompanied by significant change of coercivity is observed when approaching their ends. This local region extends just few tens of micrometer for thin (around 1 μm diameter) wires and up to several hundreds of micrometer for thick (around 10 μm diameter) wires. That predicts that critical length to observe bistability goes from 50 μm to nearly 1 mm as diameter increases from 1 to 10 μm. Results are further interpreted considering the local distribution of magnetic charges at the ends which, arising to reduce stray fields, lead in some cases to inverted loops. © 2013 American Institute of Physics.