School of Physics and Astrophysics

Postgraduate research profiles

Contact

Zoe Budrikis

Phone: (+61 8) 6488 2629


Supervisors

Start date

Mar 2008

Submission date

Mar 2012

Zoe Budrikis

Thesis

The role of array shape and vertex dynamics in the demagnetisation of ‘artificial spin ice’

Summary

In 1935, Pauling showed [1] that the extensive entropy of water ice at even very low temperatures could be explained by a simple model for the positions of hydrogen ions relative to oxygen ions, the so-called ‘ice rules’. Artificial spin ices [2, 3] are a novel type  of geometrically frustrated system described by the same rules. They consist of square [2] or hexagonal [3] arrays of sub-micron islands of magnetic material. The array geometry causes the interactions between the island magnetic moments to be frustrated, since the pairwise interactions between islands around a lattice vertex cannot be simultaneously satisfied. One of the advantages of artificial spin ices over other frustrated systems is that the interactions can be tuned by varying the lattice spacing. Of great importance in the study of artificial spin ices is the problem of demagnetisation. Experimentally, artificial spin ices are demagnetised by applying a rapidly varying magnetic field to the sample, since the islands are too large to thermally demagnetise [4].  My research is a theoretical study of the effect that array geometry, particularly at the edges of an array, has on the response of artificial spin ices to applied magnetic fields. [1] L. Pauling, Journal of the American Chemical Society 57, 2680 (1935).  [2] R. F. Wang et al., Nature 439, 303 (2006).  [3] Y. Qi, T. Brintlinger, and J. Cumings, Physical Review B (Condensed Matter and Materials Physics) 77, 094418 (2008).  [4] X. Ke et al., Physical Review Letters 101, 037205 (2008). 

Why my research is important

Experimentalists have a great deal of control over artificial spin ices, being able to do things like control interaction strengths via the island spacing and introduce defects directly by removing islands. This makes artificial spin ice systems very useful as 'model' systems for studying geometrical frustration. My theoretical work provides interpretations of experimental results and predictions that facilitate experimental design.

Funding

  • Hackett scholarship


 

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Last updated:
Monday, 2 August, 2010 2:54 PM

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