Research Institute of Electrical Communication Tohoku University

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(Takahiro Hanyu),Professor

Simon Greaves,Associate Professor

Simon Greaves

Research Activities

Our main interest lies in high-density information storage technology.
In recent years, multi-media data, such as digital movies and music, that require very large storage capacities are used in many internet and mobile communication applications, leading to a strong demand for high density information storage systems. The core technology is magnetic recording, as used in hard disk drives and magnetic tape storage, because it offers fast data transfer rates and low cost, high capacity storage. In this group we are studying recording methods, devices and systems that use perpendicular magnetic recording, which was invented at RIEC, to realize high density magnetic storage. Our aim is fast, low power consumption, high capacity terabit storage (over 5 Tbits/inch2 areal density), in which the size of each stored bit of information occupies an area of less than 10 nm by 10 nm.

Laboratory Web Page

Recording Theory Computation(Assoc. Prof. Greaves)

Micromagnetic simulations are used to model the behaviour of magnetic materials used in data storage applications. To model a recording medium the individual magnetic grains of the medium can be simulated, as shown in fig. 1. Then, using a head field distribution from a finite element model, recording simulations can be carried out. The design of the head and medium can be optimised through the model.
Other magnetic devices can also be modeled. One example is magnetic random access memory (MRAM), a non-volatile magnetic storage device. Some other examples are shown in fig. 2. Magnetic nanowires, two dimensional spin ices, domain wall pinning and energy-assisted recording are some of the topics we have worked on.

Research topics

  • Micromagnetic simulations of information storage devices
  • High areal density hard disk drives
  • Heads and disks for magnetic storage
  • Other magnetic storage devices

Fig.1 A model of a recording medium
Fig.2 Examples of micromagnetic models