Growth of cobalt nano column arrays directly on Si[111] substrate using AAO template

There is a strong demand for perpendicular magnetic storage media with a high density. Magnetic nano column array buried in a self-organized AA0 (anodic aluminum oxide) nanohole array as shown in Fig. 1 has a high potential to realize storage density above 1 tera bit / inch' [ 1 ], and a plenty of studies have been reported. However, there is a difficulty to increase coercivity of ferromagnetic nano columns enough for the ultra high-density magnetic recording, since it was difficult to control crystalline magnetic anisotropy due to the existence of amorphous alumina layer at the bottom of AA0 nanoholes as shown in Fig3(a). In this study, we established the method to remove the bottom alumina barrier layer without the loss of nanohole sidewalls, and investigated the growth of cobalt nano column directly on Si (1 ll) substrate, for aiming at control of crystalline anisotropy.