Thermal stability of metastable, epitaxial PrCo₇films with high energy density

Abstract

Two series of epitaxial Pr–Co thin films with a nominal composition of Pr2Co17 were grown on Cr buffered MgO(1 1 0) single crystal substrates by pulsed laser deposition, in which the deposition temperature TD and the post annealing temperature Tann were varied. Pr–Co films prepared at different deposition temperatures crystallize in the metastable PrCo7 structure (TbCu7 type) for 450 °C ≤ TD ≤ 650 °C. For TD ≤ 600 °C these films exhibit a (h 0 0) texture, with the c-axis of the Pr–Co grain aligned in the substrate plane along MgO[0 0 1]. However, raising TD to 650 °C, an additional out-of-plane c-axis texture is observed. Post annealing experiments on films, which are deposited at 450 °C to obtain the unique in-plane texture, reveal that crystal structure, texture and also the uniaxial magnetocrystalline anisotropy of the metastable PrCo7 structure is maintained for annealing temperatures up to 800 °C. The influence of deposition temperature and post annealing temperature on phase stability and extrinsic magnetic properties are discussed.

Stability of PrCo5+δ and Pr1−xHfxCo5+δ alloys with TbCu7-type structure at 900–1150°C and their magnetic properties

“…2(b)], the Pr 1−x Hf x Co 5+ı alloys maintain the uniaxial magnetocrystalline anisotropy with the [0 0 1] easy magnetization direction throughout the whole homogeneity range (this observation agrees with the earlier studies [12,17]). Data presented in Fig.…”

“…doi:10.1016/j.jallcom.2010.11.090 may indeed substantially increase the Curie temperature and saturation magnetization [and, therefore, the theoretical maximum energy product (BH) max ] of the uniaxially anisotropic PrCo 5 compound. Patra et al [17] recently reported epitaxial Pr-Co thin films with the TbCu 7 -type structure and a (BH) max of 43 MGOe, which is 30% higher than (BH) max of the best Sm-Co magnets. Unfortunately, epitaxial stabilization of the PrCo 5+ı structure is not possible in bulk magnets.…”

The temperature dependent anisotropy constants of epitaxially grown PrCo5+x

“…Furthermore, PrCo 5 exhibits a spin reorientation ͑SR͒ transition from an easy axis anisotropy along the crystallographic c-axis ͑which persists above the transition temperature͒ to an easy cone anisotropy around 107 K. 3 In our earlier report, 4 we revealed that epitaxial Pr-Co films ͑Ϸ80 nm͒ can be prepared on Cr buffered MgO͑110͒ substrates in a wide composition range with a single orientation of the c-axis which lies in the film plane along the MgO͓001͔ substrate edge. In that series, Pr-Co films crystallize in different phases like the PrCo 7 structure 5,6 and the PrCo 5 and Pr 2 Co 7 phases, which exist in a certain composition range. These highly textured epitaxial Pr-Co films exhibit excellent intrinsic and extrinsic magnetic properties.…”