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Calculs et simulations


OOMMF package for Dzyaloshinsky-Moriya interaction

 

Contact : S. ROHART, stanislas.rohart@u-psud.fr

 

You can download here
Oxs_DMExchange6Ngbr package
in order to include Dzyaloshinskii-Moriya interaction in the OOMMF code. It has to be included in the OOMMF code, which has been developed mainly by Donahue and Porter, and can be downloaded at this address http://math.nist.gov/oommf/.

This package includes the DMI as the interfacial isotropic formulation [A. Fert Materials Science Forum 59-60, 439 (1990)] and can describe micromagnetism in ultrathin magnetic films in interaction with high spin-orbit adjacent layers.

 

At the atomic scale, DMI is expressed as :

with d the DMI coupling energy (of the order of 1 meV), u
ij
the unit vector between atoms i and j and z the normal to the interface, oriented from the non magnetic to the magnetic layer. In the continuous form, which is implemented in OOMMF, DMI is expressed as :

with D the continuous DMI parameter (of the order of 1 mJ/m2 per bond), t the sample thickness. The link between D and d is d/at for a (001) interface and d√3/at for a (111) interface (with a the atomic distance).

 

The use of this package is similar to the Oxs_Exchange6Ngbr class.
The interface is supposed to be in the (x,y) plane.
The underlying theory and tests of this package have been published in

  • S. Rohart and A. Thiaville Phys. Rev. B 88, 184422 (2013).

Please quote this reference when using this package.

 

We used this routine in the following references :

  • A. Thiaville, S. Rohart, E. Jué, V. Cros and A. Fert EuroPhys. Lett. 100, 57002 (2012)
  • A. Fert, V. Cros and J. Sampaio Nature Nanotechnology 8, 152 (2013)
  • J. Sampaio, V. Cros, S. Rohart, A. Thiaville, A. Fert Nature Nanotechnology 8, 839 (2013)
  • O. Boulle, S. Rohart, L. D. Buda-Prejbeanu, E. Juée, M. Miron, S. Pizzini, J. Vogel, G. Gaudin, and A. Thiaville Phys. Rev. Lett. 111, 217203 (2013)
  • S. Rohart and A. Thiaville Phys. Rev. B 88, 184422 (2013)

 

One example generating skyrmions in nanodiscs is included in the package to show how it can be used. The result is shown below :


Skyrmion trapped in a 100 nm diameter nanodot [parameters : thickness = 0.6 nm, A = 16 pJ/m , D = 4 mJ/m2, Keff = 510 kJ/m3].

 

Acknowledgement

 

Xichao Zhang (Sichuan Normal University, China) updated the package for OOMMF 1.2.a4 relase.