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Giant dielectric and magnetoelectric responses in insulating nanogranular films at room temperature.

Kobayashi N, Masumoto H, Takahashi S, Maekawa S - Nat Commun (2014)

Bottom Line: In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix.Insulating nanogranular films are a new class of multifunctional materials.A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Electromagnetic Materials, 2-1-1,Yagiyama-minami, Taihaku-ku, Sendai 982-0807, Japan.

ABSTRACT
The electric and magnetic properties of matter are of great interest for materials science and their use in electronic applications. Large dielectric and magnetoelectric responses of materials at room temperature are a great advantage for electromagnetic device applications. Here we present a study of FeCo-MgF nanogranular films exhibiting giant dielectric and magnetoelectric responses at room temperature; with dielectric constant ε'=490 and magnetoelectric response Δε'/ε'0=3%. In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix. Insulating nanogranular films are a new class of multifunctional materials. The giant responses are caused by spin-dependent charge oscillation between magnetic granules via quantum-mechanical tunnelling. A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature.

No MeSH data available.


Magnetoelectric response of Fe9Co8Mg26F57 nanogranular film.Change in the dielectric constant Δε′ due to the application of magnetic field H=800 kA m−1 versus frequency f of the applied electric field for the Fe9Co8Mg26F57 (Fe+Co=17 at.%) film. The dielectric change Δε′=ε′H−ε′0 is the difference between the dielectric constants at magnetic field H and zero field H=0. The red dots represent the experimental results, and the blue solid lines represent the theoretical result obtained from calculations based on the spin-dependent dielectric-relaxation model (see equations (2) and (15)), where the tunnelling spin polarization31PT=0.44 and the magnetization normalized by the saturation magnetization M/Ms=0.62 are used.
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f4: Magnetoelectric response of Fe9Co8Mg26F57 nanogranular film.Change in the dielectric constant Δε′ due to the application of magnetic field H=800 kA m−1 versus frequency f of the applied electric field for the Fe9Co8Mg26F57 (Fe+Co=17 at.%) film. The dielectric change Δε′=ε′H−ε′0 is the difference between the dielectric constants at magnetic field H and zero field H=0. The red dots represent the experimental results, and the blue solid lines represent the theoretical result obtained from calculations based on the spin-dependent dielectric-relaxation model (see equations (2) and (15)), where the tunnelling spin polarization31PT=0.44 and the magnetization normalized by the saturation magnetization M/Ms=0.62 are used.

Mentions: Figure 4 represents the change in the dielectric constant (Δε′) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film at applied magnetic field 800 kA m−1. The dielectric constant increases by the application of magnetic field over the whole frequency range, indicating a positive magnetoelectric effect. The ratio of Δε′ and the dielectric constant in zero magnetic field ε′0 (Δε′/ε′0) is plotted as a function of H for Fe9Co8Mg26F57 film at 10 kHz in Fig. 5. This electromagnetic effect has been observed at room temperature.


Giant dielectric and magnetoelectric responses in insulating nanogranular films at room temperature.

Kobayashi N, Masumoto H, Takahashi S, Maekawa S - Nat Commun (2014)

Magnetoelectric response of Fe9Co8Mg26F57 nanogranular film.Change in the dielectric constant Δε′ due to the application of magnetic field H=800 kA m−1 versus frequency f of the applied electric field for the Fe9Co8Mg26F57 (Fe+Co=17 at.%) film. The dielectric change Δε′=ε′H−ε′0 is the difference between the dielectric constants at magnetic field H and zero field H=0. The red dots represent the experimental results, and the blue solid lines represent the theoretical result obtained from calculations based on the spin-dependent dielectric-relaxation model (see equations (2) and (15)), where the tunnelling spin polarization31PT=0.44 and the magnetization normalized by the saturation magnetization M/Ms=0.62 are used.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109019&req=5

f4: Magnetoelectric response of Fe9Co8Mg26F57 nanogranular film.Change in the dielectric constant Δε′ due to the application of magnetic field H=800 kA m−1 versus frequency f of the applied electric field for the Fe9Co8Mg26F57 (Fe+Co=17 at.%) film. The dielectric change Δε′=ε′H−ε′0 is the difference between the dielectric constants at magnetic field H and zero field H=0. The red dots represent the experimental results, and the blue solid lines represent the theoretical result obtained from calculations based on the spin-dependent dielectric-relaxation model (see equations (2) and (15)), where the tunnelling spin polarization31PT=0.44 and the magnetization normalized by the saturation magnetization M/Ms=0.62 are used.
Mentions: Figure 4 represents the change in the dielectric constant (Δε′) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film at applied magnetic field 800 kA m−1. The dielectric constant increases by the application of magnetic field over the whole frequency range, indicating a positive magnetoelectric effect. The ratio of Δε′ and the dielectric constant in zero magnetic field ε′0 (Δε′/ε′0) is plotted as a function of H for Fe9Co8Mg26F57 film at 10 kHz in Fig. 5. This electromagnetic effect has been observed at room temperature.

Bottom Line: In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix.Insulating nanogranular films are a new class of multifunctional materials.A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature.

View Article: PubMed Central - PubMed

Affiliation: Research Institute for Electromagnetic Materials, 2-1-1,Yagiyama-minami, Taihaku-ku, Sendai 982-0807, Japan.

ABSTRACT
The electric and magnetic properties of matter are of great interest for materials science and their use in electronic applications. Large dielectric and magnetoelectric responses of materials at room temperature are a great advantage for electromagnetic device applications. Here we present a study of FeCo-MgF nanogranular films exhibiting giant dielectric and magnetoelectric responses at room temperature; with dielectric constant ε'=490 and magnetoelectric response Δε'/ε'0=3%. In these films, Fe-Co alloy-based nanometer-sized magnetic granules are dispersed in a Mg-fluoride-based insulator matrix. Insulating nanogranular films are a new class of multifunctional materials. The giant responses are caused by spin-dependent charge oscillation between magnetic granules via quantum-mechanical tunnelling. A possible application of such insulating nanogranular materials with giant response is in the construction of a tunable device, in which impedance components such as capacitance and inductance are tunable at room temperature.

No MeSH data available.