Largely enhanced coercivity of FePt film at low temperature by introduction of CrRu underlayer (original) (raw)
Related papers
IEEE Transactions on Magnetics, 2000
The magnetic properties and microstructure of CrRu/FePt bilayer and CrRu/FePt/CrRu trilayer deposited by dc magnetron sputtering on preheated natural-oxidized Si (100) wafer substrates were studied. It is found that both the in-plane coercivity (Hc ) and grain size of the FePt film increase with increasing the thickness of CrRu underlayer. The Hc value of the FePt film is further increased but the grain size is decreased as adding a CrRu capped layer on the FePt film. The granular 1 0 FePt nanoparticles with in-plane coercivity of 2300 Oe and isolated uniform size of 6.61 nm are achieved from the CrRu(15 nm)/FePt(25 nm)/CrRu(4 nm) film deposited at a low substrate temperature of 350 C.
Microstructure and Magnetic Properties of FePt Multilayers and Nanoparticles
2006
a b s t r a c t By using TiC as the segregate, FePt-TiC and FePt-TiC-C thin films were prepared by co-sputtering onto strongly (002)-textured MgO/NiTa underlayer on thermally-oxidized Si substrates. The TiC effects on the microstructure and magnetic properties of L1 0 ordered FePt and FePt-C thin films were studied. The TiC segregate can refine the grain size of L1 0 ordered FePt. Coercivities and the degree of L1 0 ordering were degraded with increasing TiC concentration. By properly tuning the composition of TiC and C, the granular microstructure with average grain size of 10.3 nm and standard deviation of 1.86 nm can be achieved with the coercivity of 1.4 T. The balance between microstructure and magnetic properties indicates that mixture addition as the segregates is promising.
Magnetic properties and microstructure of low ordering temperature L1[sub 0] FePt thin films
Journal of Applied Physics, 2004
Polycrystalline Fe 52 Pt 48 alloy thin films were prepared by dc magnetron sputtering on preheated natural-oxidized silicon wafer substrates. The film thickness was varied from 10 to 100 nm. The as-deposited film was encapsulated in a quartz tube and post-annealed in vacuum at various temperatures for 1 hour, then furnace cooling. It is found that the ordering temperature from as-deposited soft magnetic fcc FePt phase to hard magnetic fct L1 0 FePt phase could be reduced to about 350 o C by preheating substrate and furnace cooling treatment. The magnetic properties measurements indicated that the in-plane coercivity of the films was increased rapidly as annealing temperature is increased from 300 o C to 400 o C, but it decreased when the annealing temperature is higher than 400 o C. X-ray diffraction analysis shown that the as-deposited FePt thin film was disorder fcc FePt phase. The magnetic measurement indicated that the transformation of disorder fcc FePt to fct L1 0 FePt phase was started at about 350 o C which is consistent with the analysis of X-ray diffraction patterns. From scanning electron microscopy (SEM) observation and selected area energy disperse spectrum (EDS) analysis, the distributions of Fe and Pt elements in the films were become non-uniform when the annealing temperature was higher than 500 o C 2 due to the formation of Fe 3 Pt phase. After annealing at 400 o C, the in plane coercivity of Fe 52 Pt 48 thin film with film thickness of 100 nm is 10 kOe, Ms is 580 emu/cm 3 , and grain size is about 12 nm.
Structural and magnetic properties of FePt films grown on Cr1-xMox underlayers
Applied Physics A, 2005
FePt films were deposited on Cr 1−x Mo x underlayers by dc magnetron sputtering. The effects of the Mo content in the underlayers, underlayer thickness, substrate temperature, and FePt film thickness on the structural and magnetic properties of the FePt films were studied. Experimental results showed that the (200) textured Cr 90 Mo 10 film was a promising underlayer for promoting the growth of the L1 0 FePt films with (001) preferred orientation at relatively low temperatures. With the Cr 90 Mo 10 underlayers, the ordering process of the FePt films could start at 200 • C. Both the ordering degree and the out-of-plane coercivity (H c ) of the FePt films increased with an increase in substrate temperature. When the substrate temperature was ≥ 250 • C, the FePt films grown on the Cr 90 Mo 10 underlayers could have the (001) preferred orientation. The FePt films grown on the Cr 90 Mo 10 underlayers at different temperatures showed a continuous microstructure. The out-of-plane coercivities H c decreased while the ordering degree increased with increased FePt film thickness, which could be due to the variation of the magnetic reversal mechanism from rotation predominant mode to domain wall motion predominant mode. PACS 68.55.Jk; 75.50.Ss
The Effects of CrV Underlayer on the Structure and Magnetic Properties of FePt Thin Film
IEEE Transactions on Magnetics, 2000
An attempt is made in this study to employ vanadium containing chromium (CrV) alloy underlayer to control the microstructure and ultimately to facilitate the in-situ ordering of Fe-Pt thin film. CrV alloys with V contents ranging from 0 to 15 at% were investigated to evaluate their effects on the magnetic properties and structural modification of FePt thin film. Addition of V in Cr underlayer results in the formation of FePt L1 0 phase with (001) preferred orientation. Analysis of XRD and HR-TEM results reveals that the lattice expansion of Cr underlayer induced by V addition increases the lattice misfit strain between CrV underlayer and FePt magnetic layer.
High coercivity FePt thin films with Ag intermediate Layers deposited at 400/spl deg/C
IEEE Transactions on Magnetics, 2000
1 0 phase FePt thin films deposited on amorphous Corning glasses and single crystal MgO (100) substrates were investigated. Epitaxial growth of the FePt (001) films was observed on MgO substrate at a deposition temperature of 400 C. With ultrathin Ag intermediate layers deposited between FePt layers, the film structure changed from interconnection network to isolated-island character. The perpendicular coercivity of the FePt film increased to about 32 kOe with intermediate layers inserted. The improvement of the magnetic properties may be attributed to the formation of island structures by the additive Ag layers in the FePt films. Index Terms-Ag, epitaxial growth, FePt, high coercivity, intermediate layer, MgO, perpendicular magnetic recording.
Magnetic hardening in FePt nanostructured films
Journal of Applied Physics, 1997
FePt films have been prepared by sputtering Fe/Pt multilayers onto glass or silicon substrates. The thickness of the Fe and Pt layers was adjusted with the Fe:Pt atomic ratio from about 1:1 to 2:1. Magnetic hardening is observed after heat treatment at elevated temperatures, which led to coercivity values exceeding 20 kOe in samples with an Fe:Pt ratio around 1.2:1. The hardening originates from the formation of the tetragonal FePt phase with high magnetocrystalline anisotropy and a favorable microstructure. Two-phase composite films containing hard and soft phases were obtained when the Fe:Pt ratio increased. Under optimized processing conditions, composite films with energy products larger than 30 MG Oe at room temperature have been successfully produced.