Nano Research

, Volume 8, Issue 4, pp 1241–1249 | Cite as

In situ electron holography of the dynamic magnetic field emanating from a hard-disk drive writer

  • Joshua F. Einsle
  • Christophe GatelEmail author
  • Aurélien Masseboeuf
  • Robin Cours
  • Muhammad A. Bashir
  • Mark Gubbins
  • Robert M. Bowman
  • Etienne Snoeck
Research Article


The proliferation of mobile devices in society accessing data via the “cloud” is imposing a dramatic increase in the amount of information to be stored on hard disk drives (HDD) used in servers. Forecasts are that areal densities will need to increase by as much as 35% compound per annum and by 2,020 cloud storage capacity will be around 7 zettabytes corresponding to areal densities of 2 Tb/in2. This requires increased performance from the magnetic pole of the electromagnetic writer in the read/write head in the HDD. Current state-of-art writing is undertaken by morphologically complex magnetic pole of sub 100 nm dimensions, in an environment of engineered magnetic shields and it needs to deliver strong directional magnetic field to areas on the recording media around 50 nm × 13 nm. This points to the need for a method to perform direct quantitative measurements of the magnetic field generated by the write pole at the nanometer scale. Here we report on the complete in situ quantitative mapping of the magnetic field generated by a functioning write pole in operation using electron holography. The results point the way towards a new nanoscale magnetic field source to further develop in situ transmission electron microscopy.


electron transmission microscopy off-axis electron holography in situ magnetic field magnetic recording hard disk write pole 


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Supplementary material

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Copyright information

© Tsinghua University Press and Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Joshua F. Einsle
    • 1
  • Christophe Gatel
    • 2
    • 3
    Email author
  • Aurélien Masseboeuf
    • 2
  • Robin Cours
    • 2
  • Muhammad A. Bashir
    • 4
  • Mark Gubbins
    • 4
  • Robert M. Bowman
    • 1
  • Etienne Snoeck
    • 2
  1. 1.Centre for Nanostructured Media, School of Mathematics and PhysicsQueen’s University BelfastBelfastUK
  2. 2.CEMES-CNRSToulouseFrance
  3. 3.Université de Toulouse Paul SabatierToulouse Cedex 9France
  4. 4.Seagate TechnologySpringtown Industrial Estate, Derry City, Co.LondonderryUK

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