Entail the new path for permanent magnets: Free-standing Hf-Co thin films

Abstract

In this work, as an alternative to permanent magnets containing rare earth, we report a method for the preparation of rare-earth-free (REF) free-standing magnetic thin films have been obtained by using a basis sacrificial layer with magnetron sputtering technique. Stoichiometric Hf34.5Co65.5 thin films are deposited on sacrificial layer coated on Si(100) substrate and removed by a selective wet-chemical etching method. Conditions for the crystallization of Hf2Co11 magnetic thin films are indicated. No crystalline peaks are found in the XRD pattern of the as-deposited film, remarking an amorphous structure. the formation of the hard magnetic orthorhombic Hf2Co11 phase requires a post-annealing at 773 K or higher until at 923 K. Freestanding Hf2Co11 thin film, which is post-annealed at 923 K, has following permanent magnet properties; H-c = 6 kOe, M-r = 370 emu.cm(-3), (BHi)(max) = 6.6 MGOe. (C) 2016 Elsevier B.V. All rights reserved.