Bistable and Multi-Domain States of α-Fe/(PrDy)(FeCo)B Ferromagnetic Microwires

In this paper, we obtained α-Fe(50 at %)(PrDy)(FeCo)B(48 at %) microwires by extraction of a hanging drop of the (PrDy)(FeCo)B melt in the electron beam. A single microwire with a diameter of 50 μm and a length of 0.8–6 mm and with an amorphous (PrDy)(FeCo)B content of ~48% and a polycrystalline α‑Fe phase of ~52% is shown to have a rectangular narrow magnetic hysteresis loop and, accordingly, a bistable state with a switching field of ~100 Oe. Shortening the wire to ~0.6 mm leads to a sharp deviation from the loop rectangularity and a decrease in the slope of the dependence of magnetization on the field and coercive force to 20 Oe. In the near-surface layers consisting of an amorphous phase (PrDy)(FeCo)B, oriented regions of reverse magnetization are observed. The role of the magnetic dipole interaction in the formation of the magnetic hysteresis loop of chaotic ensembles of microwires with various compositions is discussed.