Temperature Dependent Remanence Loops of Ion-Milled Bit Patterned Media

Magnetic multilayered thin films with perpendicular anisotropy have been patterned into nanoscale islands by ion-milling with an oxygen-plasma patterned carbon hard mask. The islands have been studied by scanning electron microscopy (SEM) and magnetic force microscopy (MFM) to determine the switching field distribution and its origin. Larger islands exhibit coercivities of ~ 450 kA/m (5.6 kOe), but coercivity falls rapidly when island diameter falls below 40 nm. The switching field distribution becomes larger in absolute terms and as a fraction of the coercivity as island diameter falls. The origin of these effects is thought to be edge damage during ion milling and intrinsic defects (grain boundaries or dislocations) in the original magnetic thin film.

[1]  Roger Wood,et al.  The feasibility of magnetic recording at 1 Terabit per square inch , 2000 .

[2]  R. Pease,et al.  Submicron patterning of thin cobalt films for magnetic storage , 1994 .

[3]  D. Weller,et al.  Recording on Bit-Patterned Media at Densities of 1 Tb/in$^2$and Beyond , 2006, IEEE Transactions on Magnetics.

[4]  Thomas Schrefl,et al.  Exchange spring media for perpendicular recording , 2005 .

[5]  H. Güntherodt,et al.  A low temperature ultrahigh vaccum scanning force microscope , 1999 .

[6]  R. Victora,et al.  Composite media for perpendicular magnetic recording , 2005, IEEE Transactions on Magnetics.

[7]  Mourad Benakli,et al.  One terabit per square inch perpendicular recording conceptual design , 2002 .

[8]  B. K. Middleton,et al.  Signal and noise characteristics of patterned media , 2002 .

[9]  R. Wood,et al.  Parametric optimization for terabit perpendicular recording , 2003, Joint NAPMRC 2003. Digest of Technical Papers.

[10]  P. Asselin,et al.  Recording on bit-patterned media at densities of 1Tb/in2 and beyond , 2006, INTERMAG 2006 - IEEE International Magnetics Conference.

[11]  High resolution magnetic force microscopy study of e-beam lithography patterned Co/Pt nanodots , 2007 .

[12]  D. Litvinov,et al.  Microstructural origin of switching field distribution in patterned Co∕Pd multilayer nanodots , 2008 .

[13]  G. Hu,et al.  Intrinsic distribution of magnetic anisotropy in thin films probed by patterned nanostructures. , 2006, Physical review letters.

[14]  Fernando Castaño,et al.  Construction of hysteresis loops of single domain elements and coupled permalloy ring arrays by magnetic force microscopy , 2003 .