Pinning energy of domain walls in MnZn ferrite films

Abstract

Mn Zn ferrite films deposited on (100) MgO substrates by rf sputtering technique with different thicknesses ξ in the range of 30-450 nm were studied. AFM images show grain size increase as film thickness increases. Grains with diameters between L ∼ 70 and 700 nm were observed. The mono and multidomain regime in MnZn ferrite films and their effect on the pinning energy of domain walls are observed via Magneto-optical Kerr Effect, MOKE. At ξ ∼ 300 nm, the coercive field, H c , reaches a maximum value of 80 Oe. This result indicates the existence of a multidomain regime associated to a critical grain size, L c . We used the Jiles-Atherton model (JAM) to discuss the experimental hysteresis loops. The k pinning parameter obtained from JAM shows a maximum value of k/µ o = 67 Am 2 for grains with L c ∼ 529 nm. The total energy per unit area E was correlated with k and D. We found a simple phenomenological relationship given by E α kD; where D is the magnetic domain width.

Modelling magnetic properties of MnZn ferrites with the modified Jiles–Atherton description

“…The domain structure of MnZn ferrites is affected by material properties such as saturation magnetization, magnetocrystalline anisotropy, grain size and distribution of defects [13,14]. The J-A macroscopic model considers hysteresis as the result of energy dissipation during domain wall translation through these defects, referred to as pinning sites [10].…”

“…Izydorczyk [20] developed a J-A identification procedure based on a linear approximation of hysteresis loops below the remanence point and using this approach modelled a wide range of commercial ferrites at room and elevated temperatures. Quite recently Calle et al [14] have used the J-A description to interpret the experimental dependences of grain size on the thickness of MnZn ferrite films and to correlate pinning site density with domain boundary energy.…”

“…For modelling purposes, all the aforementioned authors applied the sets of J-A model equations in the form disclosed either in [10] (see [19,20]) or in [21] (see [8,[14][15][16][17][18]).…”

Growth temperature dependence of the hysteretic behavior of Ni0.5Zn0.5Fe2O4 thin films

“…The limit between the coupled-grain and the single-grain regions is indicated by the dashed line inFig. 3.We used the Jiles-Atherton Model[7,10] to fit the experimental hysteresis loops obtained by MOKE. The Jiles-Atherton Model is based on domain wall motion of an irreversible component due to wall displacement and a reversible component due to domain wall bending.…”