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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.


Related in: MedlinePlus

Structure and electric polarization of a nanogranular film.(a) A schematic of a nanogranular film with nanometer-sized granules dispersed in an insulator matrix. The right-side figure in a represents a schematic of the electric potential profile of two granules in an ac electric field that generate oscillating transition of an electric charge carrier (electron, hole) between them via quantum-mechanical tunnelling through the thin insulating barrier. The oscillating transition of the charge-carrier with spin depends on the relative orientation of the magnetization of the granules. This spin-dependent charge oscillation is the origin of the dielectric and magnetoelectric (magneto-dielectric) responses of the nanogranular films. (b) A high-resolution transmission electron microscope image (in plain) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film of a typical sample (scale bar, 10 nm).
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f1: Structure and electric polarization of a nanogranular film.(a) A schematic of a nanogranular film with nanometer-sized granules dispersed in an insulator matrix. The right-side figure in a represents a schematic of the electric potential profile of two granules in an ac electric field that generate oscillating transition of an electric charge carrier (electron, hole) between them via quantum-mechanical tunnelling through the thin insulating barrier. The oscillating transition of the charge-carrier with spin depends on the relative orientation of the magnetization of the granules. This spin-dependent charge oscillation is the origin of the dielectric and magnetoelectric (magneto-dielectric) responses of the nanogranular films. (b) A high-resolution transmission electron microscope image (in plain) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film of a typical sample (scale bar, 10 nm).

Mentions: Figure 1a illustrates a nanogranular structure, which consists of nanometer-sized magnetic granules dispersed in an insulator matrix. Figure 1b shows a high-resolution transmission electron microscope image obtained from Fe9Co8Mg26F57 (Fe+Co=17 at.%) thin film, which is one of the samples produced in this study. In this micrograph, many small dark and deformed circles with diameters ranging from about 2 to 4 nm are observed. In addition, a bright network-like pattern covering the whole area is identified. The dark deformed circles are Fe-Co alloy-based granules, and the small bright section indicates the Mg-fluoride-based matrix.


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

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

Structure and electric polarization of a nanogranular film.(a) A schematic of a nanogranular film with nanometer-sized granules dispersed in an insulator matrix. The right-side figure in a represents a schematic of the electric potential profile of two granules in an ac electric field that generate oscillating transition of an electric charge carrier (electron, hole) between them via quantum-mechanical tunnelling through the thin insulating barrier. The oscillating transition of the charge-carrier with spin depends on the relative orientation of the magnetization of the granules. This spin-dependent charge oscillation is the origin of the dielectric and magnetoelectric (magneto-dielectric) responses of the nanogranular films. (b) A high-resolution transmission electron microscope image (in plain) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film of a typical sample (scale bar, 10 nm).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: Structure and electric polarization of a nanogranular film.(a) A schematic of a nanogranular film with nanometer-sized granules dispersed in an insulator matrix. The right-side figure in a represents a schematic of the electric potential profile of two granules in an ac electric field that generate oscillating transition of an electric charge carrier (electron, hole) between them via quantum-mechanical tunnelling through the thin insulating barrier. The oscillating transition of the charge-carrier with spin depends on the relative orientation of the magnetization of the granules. This spin-dependent charge oscillation is the origin of the dielectric and magnetoelectric (magneto-dielectric) responses of the nanogranular films. (b) A high-resolution transmission electron microscope image (in plain) of Fe9Co8Mg26F57 (Fe+Co=17 at.%) film of a typical sample (scale bar, 10 nm).
Mentions: Figure 1a illustrates a nanogranular structure, which consists of nanometer-sized magnetic granules dispersed in an insulator matrix. Figure 1b shows a high-resolution transmission electron microscope image obtained from Fe9Co8Mg26F57 (Fe+Co=17 at.%) thin film, which is one of the samples produced in this study. In this micrograph, many small dark and deformed circles with diameters ranging from about 2 to 4 nm are observed. In addition, a bright network-like pattern covering the whole area is identified. The dark deformed circles are Fe-Co alloy-based granules, and the small bright section indicates the Mg-fluoride-based matrix.

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.


Related in: MedlinePlus