Chemical stability of highly (0001) textured Sm(CoCu){sub 5} thin films with a thin Ta capping layer

Journal Article · Fri Apr 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3548833· OSTI ID:21560101

Haibao, Zhao; Hao, Wang; Xiaoqi, Liu; Jianping, Wang ^[1]; Tao, Zhang ^[2]

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1. MINT Center, Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)
2. RMO, Seagate Technology, Fremont, California 94538 (United States)

With the highest magnetocrystalline anisotropy constant (Ku) among practical magnetic materials, SmCo{sub 5} could be a very attractive candidate for future high areal density magnetic recording. However, its corrosion resistance is always a concern in recording media applications. In this paper, the chemical stability and microstructures of highly (0001) textured Sm(CoCu){sub 5} thin films with and without a 3 nm Ta capping layer were reported. For Sm(CoCu){sub 5} thin films without a capping layer, the coercivity decreases significantly (from 8kOe to 1kOe) within one month. Sm(CoCu){sub 5} thin films capped with a thin Ta layer (3 nm) behave differently. Even exposed to a laboratory environment (25 deg. C) over 3 years, the Ta-capped Sm(CoCu){sub 5} thin films are stable in terms of structural and magnetic properties, i.e., there were no changes in X-ray diffraction peaks and vibrating sample magnetometer hysteresis loops. Microstructure of Ta-capped Sm(CoCu){sub 5} thin films showed that Sm(CoCu){sub 5} formed a domelike particle assembly structure on a smooth Ru underlayer and were well covered by partially oxidized Ta capping layer, as shown by TEM cross-section micrographs. Accelerated corrosion treatment (130 deg. C, 95% relative humidity, 6 h) was performed on Ta-capped Sm(CoCu){sub 5} thin films. X-ray photoelectron spectroscopy (XPS) results showed that no Co was detected on the sample surface before the corrosion treatment, but strong XPS signals of CoOx and Co(OH)x were observed after treatment. Therefore, none of our Sm(CoCu){sub 5} thin films can pass the accelerated corrosion test. Hcp-phased CoPt-alloys are proposed as better capping materials for Sm(CoCu){sub 5} thin films in future high-density magnetic recording applications.

• OSTI ID: 21560101
• Journal Information: Journal of Applied Physics, Vol. 109, Issue 7; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: DOI: 10.1063/1.3548833; (c) 2011 American Institute of Physics; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
COBALT ALLOYS
COERCIVE FORCE
COPPER ALLOYS
CORROSION RESISTANCE
CROSS SECTIONS
HCP LATTICES
HYSTERESIS
LAYERS
MAGNETIC MATERIALS
MAGNETIC PROPERTIES
MICROSTRUCTURE
SAMARIUM ALLOYS
STABILITY
SURFACES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
VIBRATING SAMPLE MAGNETOMETERS
X-RAY DIFFRACTION
X-RAY PHOTOELECTRON SPECTROSCOPY
ALLOYS
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
FILMS
HEXAGONAL LATTICES
MAGNETOMETERS
MATERIALS
MEASURING INSTRUMENTS
MICROSCOPY
PHOTOELECTRON SPECTROSCOPY
PHYSICAL PROPERTIES
RARE EARTH ALLOYS
SCATTERING
SPECTROSCOPY
TRANSITION ELEMENT ALLOYS