Magnetic properties of Nd-Fe-B/α-Fe multi-layered thick film magnets

Nd-Fe-B/α-Fe multi-layered nanocomposite film-magnets were prepared from a rotating Nd2.6Fe14B/α-Fe composite target by the pulse laser deposition method with a Nd-YAG laser (λ=355 nm). The prepared film-magnets were composed of approximately 800 layers with the thickness of about several tens nanometre, and exhibited hard magnetic properties after annealing. The laser power for the ablation of the target was varied between 3 and 7 W, and it was found that the composition, magnetic properties, and the surface roughness of the prepared films depend on the laser power. A reduction in the laser power caused increases in remanence and the maximum energy product (BH)max as well as decreases in Nd content and coercivity of the films. All the samples had Nd-poor compositions compared with that of the Nd2.6Fe14B target and the Nd-contents of the films deposited with laser power of 3 W were less than that of the stoichiometric composition of Nd2Fe14B. The highest (BH)max and remanence values were obtained for a film deposited with laser power of 3 W, and were 90 kJ/m3 and 1.0 T, respectively. The obtained high remanence value is discussed from the viewpoint of the remanence enhancement as well as the large saturation magnetization of α-Fe.

[1]  K. Ishiyama,et al.  Investigation on Magnetic Torque of Multi-Polarly Micro Rotor Using Shape-Magnetic-Anisotropy , 2010, IEEE transactions on magnetics.

[2]  K. Ishiyama,et al.  Review of Fabrication and Characterization of Nd–Fe–B Thick Films for Magnetic Micromachines , 2007, IEEE Transactions on Magnetics.

[3]  A. Walther,et al.  High performance hard magnetic NdFeB thick films for integration into micro-electro-mechanical systems , 2007, cond-mat/0703785.

[4]  Hans H. Gatzen,et al.  Thin film SmCo magnets for use in electromagnetic microactuators , 2006 .

[5]  M. Nakano,et al.  Magnetic properties of Nd–Fe–B nanocomposite films prepared by a new method using pulsed laser deposition , 2006 .

[6]  H. Nakamura,et al.  Magnetic properties of extremely small Nd-Fe-B sintered magnets , 2005, IEEE Transactions on Magnetics.

[7]  稔 上原.  多層Nd-Fe-B/Ta垂直磁化薄膜の微細組織と磁気特性 , 2004 .

[8]  B. Pawlowski,et al.  Permanent magnetic thick films from remanence optimized NdFeB-inks , 2004 .

[9]  B. Pawlowski,et al.  NdFeB thick films prepared by tape casting , 2003 .

[10]  Masaki Nakano,et al.  Magnetic properties of Nd-Fe-B thick film magnets prepared by laser ablation technique , 2002 .

[11]  W. Unterberg,et al.  Nd–Fe–B permanent magnets (thick films) produced by a vacuum-plasma-spraying process , 2000 .

[12]  H. Fukunaga,et al.  Effect of strength of intergrain exchange interaction on magnetic properties of nanocomposite magnets , 1999, IEEE International Magnetics Conference.

[13]  T. Miyazaki,et al.  Magnetic properties of exchange-coupled α-Fe/Nd–Fe–B multilayer thin-film magnets , 1997 .

[14]  N. Kornilov,et al.  Sputtered permanent Nd-Fe-B magnets , 1993 .

[15]  Jiro Yamasaki,et al.  Anisotropic Nd–Fe–B thin‐film magnets for milli‐size motor , 1991 .

[16]  E. Kneller,et al.  The exchange-spring magnet: a new material principle for permanent magnets , 1991 .