Berlin 2008 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 23: Poster session

MM 23.23: Poster

Dienstag, 26. Februar 2008, 14:45–18:00, Poster B

Field-driven evolution of stripe domains in magnetic shape memory alloy films — Nikolay S. Kiselev^1,2, Igor E. Dragunov², Aristide T. Onisan¹, •Ulrich K. Rößler¹, and Alexei N. Bogdanov^1,2 — ¹IFW Dresden — ²Donetsk Institute for Physics and Technology

A phenomenological approach is used to describe the redistribution of martensitic variants driven by an external magnetic field in ferromagnetic shape memory materials. Real samples of magnetic shape memory alloys as the Ni-Mn-Ga Heusler alloys contain complex systems of crystallographic and magnetic domains [1, 2]. Magnetic reversal in such system is characterized by particular effects including the existence of 180-degree magnetic domain structures within the twin variants and the rotation of magnetic moments within magnetic domains in case of relatively weak magnetic anisotropies [1]. An elementary model for these complicated systems is proposed by using the ``one-to-one correspondence'' between magnetic domains and martensite variants [3]. For this model, we calculate stability ranges and evolution of equilibrium and metastable stripe states [3] and isolated twin-variants in thin single-crystalline plates. We discuss the applicability of this model to describe nucleation and magnetization processes in real samples.

[1] Y. W. Lai et al., Appl. Phys. Lett. 90 (2007) 192504; [2] V. A. Chernenko et al., Acta Mater. 53 (2006) 5461. [3] N. S. Kiselev et al., Eur. Phys. J. Special Topics, to appear.