Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 23: Poster session
MM 23.45: Poster
Dienstag, 26. Februar 2008, 14:45–18:00, Poster B
Correlated ferroelastic/ferromagnetic domain walls in ultrathin films: observations and physical description — •Catherine Jenkins1,2, R Ramesh1, and Gerhard Jakob2 — 1University of California, Berkeley — 2Johannes Gutenberg-Universität Mainz
The magnetic shape memory (MSM) effect is when simultaneously occurring ferromagnetic and ferroelastic domain walls form a twin boundary system that is actuated in one of three ways: by a magnetic field, a mechanical stress, or heating. Thin films of MSM alloys are exciting candidates for research because of the many variables that can be efficiently explored in a single system, and are promising for technological development for their novel magnetic and electronic characteristics.
Theoretical predictions in the literature (1), along with a physical understanding of the processes involved (2) together suggest that the thermoelastic austenite to martensite phase transition that allows for the 'memory' can be explored with temperature-dependent atomic force microscopy, as we show experimentally in fairly thick films of another shape memory alloy, nickel titanium. The behaviour of ultrathin films is expected to be noticeably different due to strong epitaxial clamping effects. In this work the expected topographic behaviour of ultrathin shape memory alloys during a magnetically and thermally induced phase transition and evolution is described and preliminary measurements presented.
1. Bertram HN, Paul DI, J Appl. Phys., vol.82, no.5, 1997, p. 2439
2. S. J. Murray et al, J. Appl. Phys., vol. 87, No. 9, 2000, p. 5774