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Article Dans Une Revue Applied Physics Letters Année : 2011

Origin of magnetic switching field distribution in bit patterned media based on pre-patterned substrates

Résumé

Using a combination of synchrotron radiation based magnetic imaging and high-resolution transmission electron microscopy we reveal systematic correlations between the magnetic switching field and the internal nanoscale structure of individual islands in bit patterned media fabricated by Co/Pd-multilayer deposition onto pre-patterned substrates. We find that misaligned grains at the island periphery are a common feature independent of the island switching field, while irregular island shapes and misaligned grains specifically extending into the center of an island are systematically correlated with a reduced island reversal field. Bit patterned media (BPM) is a leading candidate for extending high-density magnetic recording in hard disk drives beyond 1 Tb/in 2. BPM technology aims at increasing the recording density by pre-defining the bits, i.e., the magnetic volume storing one information unit, as lithographically separated islands. 1 The bit-to-bit variation of the coercive fields is expressed in the switching field distribution (SFD). In order to reliably write a bit, i.e., to reverse the magnetization of an island, the SFD of the island array has to be sufficiently narrow. Currently the controlled reduction of the SFD remains a major challenge in the development of BPM. The SFD is determined by two different contributions. 2 First the magnetic islands are influenced by the stray fields of neighboring islands. In case of perpendicular anisotropy systems that are especially considered for applications in BPM the stray fields from neighbors tend to broaden the SFD. Second the switching field of every single island is influenced by its individual properties. Due to island-to-island variations of these properties , the switching fields show a so-called intrinsic distribution. Variations in island reversal fields are assumed to be induced by variations of the magnitude or direction of the local anisotropy, such as originating from island size, shape, composition, and (crystalline) structure as well as localized strain, corrupted island edges, or misaligned grains. 3–7
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Dates et versions

hal-01345365 , version 1 (13-07-2016)

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B Pfau, C.M. Günther, E Guehrs, Thomas Hauet, H Yang, et al.. Origin of magnetic switching field distribution in bit patterned media based on pre-patterned substrates. Applied Physics Letters, 2011, ⟨10.1063/1.3623488⟩. ⟨hal-01345365⟩
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