Energy barriers in patterned media

Magnetic interactions in 2D and 3D arrays

“…with dimensions comparable to the exchange length [Hubert and Schäfer, 1998]. For our media, the exchange length is 4 nm [de Vries, 2013].…”

“…The primary focus is on 2D arrays of patterned magnetic islands [de Vries, 2013;Murillo Vallejo, 2006], which are prototypical hard disk drive (HDD) recording media. I have researched the interaction involved in reading and writing such media, theoretically by means of modeling and simulations, and experimentally using magnetic force microscopy.…”

“…After transferring the pattern, the BARC was removed, although we cannot exclude the possibility that some BARC residue may remain on top of the islands. Details of the LIL patterning are given in [de Vries, 2013].…”

“…Our experiments are however conducted at room temperature with finite durations of the field pulses (1 s). This lowers the switching fields considerably from their 0 K value [de Vries, 2013]. Besides this, thermal fluctuations require that switching fields must in principle be treated as stochastic quantities.…”

“…Nucleation and depinning barriers have distinct dependencies on the applied field. Experimentally, the barrier height is determined by the statistical fluctuations of the switching fields [Engelen et al, 2010;de Vries et al, 2013], or by the dependence of the switching fields on temperature [de Vries, 2013;Okamoto et al, 2008;Shaw et al, 2008] or applied field duration [Adam et al, 2012;Mitsuzuka et al, 2007;Okamoto et al, 2008;Springer et al, 2011;Tudosa et al, 2012]. These experiments are all challenging and, on their own, possibly not decisive [Adam et al, 2012;Engelen et al, 2010;de Vries et al, 2013].…”