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Nanoscale Magnetic Characterization of Tunneling Magnetoresistance Spin Valve Head by Electron Holography
Author(s) -
Park Hyun Soon,
Hirata Kei,
Yanagisawa Keiichi,
Ishida Yoichi,
Matsuda Tsuyoshi,
Shindo Daisuke,
Tonomura Akira
Publication year - 2012
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201201365
Subject(s) - electron holography , materials science , condensed matter physics , spin valve , magnetoresistance , magnetization , magnetic field , nanoscopic scale , nanostructure , electron , quantum tunnelling , giant magnetoresistance , optoelectronics , nanotechnology , physics , transmission electron microscopy , quantum mechanics
Nanostructured magnetic materials play an important role in increasing miniaturized devices. For the studies of their magnetic properties and behaviors, nanoscale imaging of magnetic field is indispensible. Here, using electron holography, the magnetization distribution of a TMR spin valve head of commercial design is investigated without and with a magnetic field applied. Characterized is the magnetic flux distribution in complex hetero‐nanostructures by averaging the phase images and separating their component magnetic vectors and electric potentials. The magnetic flux densities of the NiFe (shield and 5 nm‐free layers) and the CoPt (20 nm‐bias layer) are estimated to be 1.0 T and 0.9 T, respectively. The changes in the magnetization distribution of the shield, bias, and free layers are visualized in situ for an applied field of 14 kOe. This study demonstrates the promise of electron holography for characterizing the magnetic properties of hetero‐interfaces, nanostructures, and catalysts.