MAGNETIC DOMAIN PINNING IN PATTERNED DyFeCo FOR THE APPLICATION OF MAGNETO-OPTICAL RECORDING

Abstract

-A method for pinning magnetic domains with prescribed shapes has been developed for the magnetooptical (MO) thin film material DYx(FeCo)J.x. The pinning array of holes on the substrate was fabricated using electron beam lithography. The thin film of DYx(FeCo)l.x sandwiched between SiN layers was deposited onto a patterned polymethyl methacrylate (PM MA) layer. The pinned domains acquire the shape of the holes, while the sharpness of their boundaries depends on the size of the holes. The stability of the pinned domains is affected by the sample's magnetization. In our experiments, the minimum stable domain size pinned within the hole arra)-\\as found to be around 30 nm in diameter.

Magnetic Domain Pinning in Lithographically Patterned Amorphous Magnetic Layer

“…That the ridges show broader in magnetic image than in morphology is due to the natural divergence of the magnetic filed. Apparently, the magnetic domains were pinned inside the radial hole array and resembled the geometric shapes of the radial perpendicular magnetization on the side-walls and in the bottom areas of the hole as described by Wu et al 7,8) The coercivity of the patterned MO layer was found to be much higher than in the unpatterned MO layer (almost twice higher), moreover within the patterned area the coercivity was higher in the larger pinning sites than in the smaller pinning sites. The magnetic domains were found to be pinned inside the radial hole array and resembled the geometric shapes of the hole array.…”

“…We have developed a technique of using pre-formatted gold structures, superior to the previous PMMA method, 7,8) for the studies of the magnetic domain pinning behavior. The pinning mechanism is believed to be the combination vector effect of gold grid.…”

“…[3][4][5] One way to overcome the problem is to provide artificial pinning sites in the continuous magnetic films as originally proposed by Gadetsky et al, 6) in which a photolithography was used. In carrying the idea but for the sake of higher data storage density, we have shown denser and smaller pinning domains by using electron beam lithography, 7,8) in which the artificial pinning sites were made in the hole array of polymethyl methacrylate (PMMA). PMMA, however, has certain deficiencies such as it peels off from the substrate easily, which is resulted from cracking during the sputtering of MO film.…”