Magnetic anisotropy and crystalline texture in BaO(Fe2O3)6 thin films deposited on GaN∕Al2O3

Abstract

Ba O ( Fe 2 O 3 ) 6 (BaM) thin films were deposited by pulsed laser deposition on GaN∕Al2O3 substrates. A pole figure obtained from the (006) reflection indicated that ∼81% of the film volume had the c axis tilted less than 5° from the film normal. A low anisotropy field was inferred from vector coil vibrating sample magnetometer (VVSM) measurements. The reduction in Ha from literature values and a two-step switching of the easy axis magnetization is postulated to result from interdiffusion and misalignment effects. To alleviate interdiffusion and to improve the c-axis alignment, experiments were repeated with lower deposition temperatures, thinner films, and MgO buffer layers. The features of the hysteresis loop due to two-step switching and the in-plane coercivity were reduced while the anisotropy field (Ha) was larger. Films deposited with MgO buffer layers are observed to have single-step switching of the easy axis magnetization, larger anisotropy fields, and sharp ferromagnetic resonance (FMR) peaks. Films with MgO buffer layers were determined to have anisotropy fields Ha=1.57T by FMR and Ha∼1.5–1.6T as determined from the difference in the saturation fields for the easy and hard axis loops.