Dynamic observation of field induced twin boundary and magnetic domain wall motion in bulk NiMnGa
|Ryan Yiu Wai Lai , Jeffrey McCord , Nils Scheerbaum , Oliver Gutfleisch , Rudolf Schäfer , Ludwig Schultz|
Leibniz-Institute for Solid State and Materials Research, P.O.Box 270116, Dresden D-01171, Germany
A study of twin boundary movement in NiMnGa shape memory single crystals in connection with in-situ magnetic domain observation is presented. Time-resolved polarization microscopy, using a magneto-optical indicator film technique, was applied to record the magnetic domain pattern’s reorganization during the process. No magnetic domain wall movement is observed during twin boundary motion, which is different from previously proposed model. Moreover, a dynamic actuation experimental setup with the ability to apply mechanical stress and alternating magnetic field perpendicularly is developed in cooperation with time-resolved microscopy. Reversible twin boundary motion activated in the frequency range up to 200Hz is directly observed. Hysteresis curves of magnetic field induced strain in different frequencies show the dependence of twin boundary motion with excitation field frequency. Funding through the DFG priority program SPP1239 is gratefully acknowledged.
Presentation: Oral at E-MRS Fall Meeting 2007, Symposium E, by Ryan Yiu Wai Lai
See On-line Journal of E-MRS Fall Meeting 2007
Submitted: 2007-05-21 10:14 Revised: 2009-06-07 00:44