Nanocomposites and nanomaterials

Radial and longitudinal magnetic domains in (PrDy)(FeCo)B microwires 
O.V.Koplak, R.B. Morgunov 
Institute of Problems of Chemical Physics,
Academician Semenov av. 1, Chernogolovka, 142432 Russian Federation
E-mail: o.koplak@gmail.com

Ferromagnetic microneedles, mirowires attract an attention of specialists due to new fundamental phenomena and wide practical application as magnetic sensors. The (PrDy)(FeCo)B microwires of 19-105 μm diameters containing amorphous PrDyFeCoB phase and microcrystalline inclusions were grown by pendant melt drop technique and analyzed in this work. Magneto-optical techniques reveal radial domains corresponding to complicate magnetic structure near surface (Fig 1a). Dependences of radial domain density and average domain width strongly depends on microwire diameter (Fig 1b, c).

Fig. 1. (a) Perpendicular component of magnetization in microwire placed in longitudinal magnetic field; (b) Dependences of radial domain density n on magnetic field in microwires with diameters 60(1), 70(2), 75(3), 90(4), 100(5), 105(6) μm; (c) Dependence of the average domain width D on microwire diameter d in magnetic field 1 kOe; (d) Angular dependences of magnetic moment for the sample measured in 1 - 10 kOe range.

Biaxial model of magnetic anisotropy satisfactorily describes angular and field dependences of magnetization of the microwires in the frame of the Stoner-Wohlfarth formalism (Fig 1d). Coexistence of longitudinal magnetized core, basically contributing to magnetization, and radial magnetized shell divided onto domains with small contribution to magnetization were revealed.