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Giant Magnetostrain Based on Strong Single Ion Anisotropy of Rare Earth Materials

Mathias Doerr 1Sebastian Raasch 1Martin Rotter 4Matthias Frontzek 1Dirk C. Meyer 2Manuel Zschintzsch 2Pavel Svoboda 3Michael Loewenhaupt 1

1. Technische Universität Dresden, Institut für Festkörperphysik, Dresden D-01062, Germany
2. Technische Universität Dresden, Institut für Strukturphysik, Dresden D-01062, Germany
3. Charles University Prague, Dept. of Electronic Structures, Prague CZ-12116, Czech Republic
4. Universität Wien, Institut für Physikalische Chemie, Währingerstr. 42, Wien A-1090, Austria

The volume, shape and microstructure of solids can be influenced by magnetic fields [1]. Much effort is focused on magnetic shape memory (MSM) materials. Recently, the MSM effect has been discovered to occur also in the paramagnetic state, e.g. in RCu2 compounds (R = rare earth) [2]. RMSM materials distinguish themselves from conventional MSM materials by the new origin of the magneto-crystalline anisotropy: the strong rare-earth single ion anisotropy. Due to the pseudo-hexagonal symmetry of RCu2, three orientational variants exists, each of them rotated by about 60 deg with respect to the others. Switching these variants by an external field results in a change of the macroscopic shape. The strain is in the order of one percent (= Giant MagnetoStrain). The variant´s fraction stays unchanged still after ramping down the field. The virgin state can be recovered by heating or by a perpendicularly directed field. This irreversibility shows the potential to construct field controlled actuators or switches.

We present temperature and field dependent measurements of magnetostrain and magentization at the model substance Tb0.5Dy0.5Cu2. The macroscopic characterization of the sample is complemented by a detailed microscopic analysis done by elastic neutron scattering. Although the GMS effect of RCu2 was worked out at single crystals, the principle of this magneto-mechanical coupling phenomenon is also useful for polycrystalline or microscaled applications. Futural preparation and characterization of thin or free-standing films are necessary to contsruct micro-mechanical actuators.

[1] M. Doerr et al.: Adv. Phys. 54 (2005) 1.

[2] S. Raasch et al.: Phys. Rev. B 73 (2005) 64402.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium E, by Mathias Doerr
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-03-27 14:35
Revised:   2009-06-07 00:44