ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Recently, there has been much interest in the noise characteristics of recording media.1 These characteristics have not been completely explained by current theoretical models.2 This paper reports on the noise characteristics as a function of write current and its correlation with written bits as observed by SEMPA.3–5 CoNiCr film sputtered on Al-based NiP substrate was used for this study. The grain structure of this sample was obtained by high-resolution SEM, and the magnetic microstructure was observed by utilizing the SEMPA technique. The saturation magnetization MS and coercivity HC for this film are 731 emu/cc and 794 Oe, respectively. The noise measurements show that as the write current is increased from zero, a well-defined noise maximum is observed at a write current of about 8.5 mA o-p. With further increase in write current, noise voltage decreases to a minimum at about 14 mA o-p, and then rises again showing a secondary, broad noise maximum at a write current of about 34 mA o-p. The SEMPA images of the written transitions at those three write currents of 8.5, 14, and 34 mA o-p have been obtained. These SEMPA images show a strong correlation with the noise behavior of this media. At the first noise maxima, where the signal amplitude is high, the magnetized regions show some cross links and the transition region shows irregularities. For the intermediate write current where noise is low, the cross links between the magnetized regions are minimal. At the secondary maximum, where the readback signal amplitude is very low, the magnetized regions are heavily overlapped and there is practically no identifiable transition regions as observed by SEMPA. The micromagnetic structure of a reverse dc erase track at the noise maximum has also been observed by SEMPA and will be reported along with the noise data.5 The details of this paper appear in Ref. 5.〈ks〉
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.348268
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