TY - JOUR
T1 - Computational and experimental investigations of magnetic domain structures in patterned magnetic thin films
AU - Li, Yulan
AU - Xu, Ke
AU - Hu, Shenyang
AU - Suter, Jon
AU - Schreiber, Daniel K.
AU - Ramuhalli, Pradeep
AU - Johnson, Bradley R.
AU - McCloy, John
N1 - Publisher Copyright:
© 2015 IOP Publishing Ltd.
PY - 2015/8/5
Y1 - 2015/8/5
N2 - The use of nondestructive magnetic signatures for continuous monitoring of the degradation of structural materials in nuclear reactors is a promising yet challenging application for advanced functional materials behavior modeling and measurement. In this work, a numerical model, which is based on the Landau-Lifshitz-Gilbert equation of magnetization dynamics and the phase field approach, was developed to study the impact of defects such as nonmagnetic precipitates and/or voids, free surfaces and crystal orientation on magnetic domain structures and magnetic responses in magnetic materials, with the goal of exploring the correlation between microstructures and magnetic signatures. To validate the model, single crystal iron thin films (∼240 nm thickness) were grown on MgO substrates and a focused ion beam was used to pattern micrometer-scale specimens with different geometries. Magnetic force microscopy (MFM) was used to measure magnetic domain structure and its field-dependence. Numerical simulations were constructed with the same geometry as the patterned specimens and under similar applied magnetic field conditions as tested by MFM. The results from simulations and experiments show that 1) magnetic domain structures strongly depend on the film geometry and the external applied field and 2) the predicted magnetic domain structures from the simulations agree quantitatively with those measured by MFM. The results demonstrate the capability of the developed model, used together with key experiments, for improving the understanding of the signal physics in magnetic sensing, thereby providing guidance to the development of advanced nondestructive magnetic techniques.
AB - The use of nondestructive magnetic signatures for continuous monitoring of the degradation of structural materials in nuclear reactors is a promising yet challenging application for advanced functional materials behavior modeling and measurement. In this work, a numerical model, which is based on the Landau-Lifshitz-Gilbert equation of magnetization dynamics and the phase field approach, was developed to study the impact of defects such as nonmagnetic precipitates and/or voids, free surfaces and crystal orientation on magnetic domain structures and magnetic responses in magnetic materials, with the goal of exploring the correlation between microstructures and magnetic signatures. To validate the model, single crystal iron thin films (∼240 nm thickness) were grown on MgO substrates and a focused ion beam was used to pattern micrometer-scale specimens with different geometries. Magnetic force microscopy (MFM) was used to measure magnetic domain structure and its field-dependence. Numerical simulations were constructed with the same geometry as the patterned specimens and under similar applied magnetic field conditions as tested by MFM. The results from simulations and experiments show that 1) magnetic domain structures strongly depend on the film geometry and the external applied field and 2) the predicted magnetic domain structures from the simulations agree quantitatively with those measured by MFM. The results demonstrate the capability of the developed model, used together with key experiments, for improving the understanding of the signal physics in magnetic sensing, thereby providing guidance to the development of advanced nondestructive magnetic techniques.
KW - LLG equation
KW - iron thin films
KW - magnetic force microscopy
KW - nondestructive magnetic signatures
KW - phase field approach
UR - http://www.scopus.com/inward/record.url?scp=84937022259&partnerID=8YFLogxK
U2 - 10.1088/0022-3727/48/30/305001
DO - 10.1088/0022-3727/48/30/305001
M3 - Article
AN - SCOPUS:84937022259
SN - 0022-3727
VL - 48
JO - Journal of Physics D: Applied Physics
JF - Journal of Physics D: Applied Physics
IS - 30
M1 - 305001
ER -