Crystal structure, anisotropy and spin reorientation transition of highly coercive, epitaxial Pr-Co films

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Epitaxial Pr-Co thin ¯lms were prepared by pulsed laser deposition on di®erent sur-
face orientations of MgO single crystal substrates, and their phase formation range,
crystal structure, texture, intrinsic and extrinsic magnetic properties were examined.
Furthermore, due to the orientation of the crystallographic c-axis of the Pr-Co grains
along well de¯ned substrate directions the magnetocrystalline anisotropy could be
analyzed.
Depending upon the composition, di®erent Pr-Co phases (such as PrCo5 and
Pr2Co7) are observed. Moreover, a metastable binary PrCo7 structure with a uni-
axial anisotropy has been stabilized which has no bulk counterpart. A temperature-
composition phase diagram, classifying the magnetocrystalline anisotropy into easy
axis and easy cone has been established. From the measurement of angle dependent
magnetization loops at various temperatures the anisotropy constants K1 and K2
of a Pr15:4Co84:6 ¯lm are determined. The temperature dependency of K1 and K2
follows the behavior known for PrCo5 single crystals and manifests the occurrence
of a spin reorientation at about 108 K.