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Nanometer-size hard magnetic ferrite exhibiting high optical-transparency and nonlinear optical-magnetoelectric effect.

Ohkoshi S, Namai A, Imoto K, Yoshikiyo M, Tarora W, Nakagawa K, Komine M, Miyamoto Y, Nasu T, Oka S, Tokoro H - Sci Rep (2015)

Bottom Line: Additionally, we have observed magnetization-induced second harmonic generation (MSHG).The nonlinear optical-magnetoelectric effect of the present polar magnetic nanocrystal was quite strong.These findings have been demonstrated in a simple iron oxide, which is highly significant from the viewpoints of economic cost and mass production.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

ABSTRACT
Development of nanometer-sized magnetic particles exhibiting a large coercive field (Hc) is in high demand for densification of magnetic recording. Herein, we report a single-nanosize (i.e., less than ten nanometers across) hard magnetic ferrite. This magnetic ferrite is composed of ε-Fe2O3, with a sufficiently high Hc value for magnetic recording systems and a remarkably high magnetic anisotropy constant of 7.7 × 10(6) erg cm(-3). For example, 8.2-nm nanoparticles have an Hc value of 5.2 kOe at room temperature. A colloidal solution of these nanoparticles possesses a light orange color due to a wide band gap of 2.9 eV (430 nm), indicating a possibility of transparent magnetic pigments. Additionally, we have observed magnetization-induced second harmonic generation (MSHG). The nonlinear optical-magnetoelectric effect of the present polar magnetic nanocrystal was quite strong. These findings have been demonstrated in a simple iron oxide, which is highly significant from the viewpoints of economic cost and mass production.

No MeSH data available.


Related in: MedlinePlus

Particle size dependence of the magnetic properties.(a) Magnetic hysteresis loops of S-1020, S-1044, S-1063, and S-1142 measured at 300 K with an illustration of the average particle size. (b) Hc value at 300 K with random orientation versus d plot. The red line is a guide for the eye, which was drawn based on the d dependence equation of Hc, taking into account the random orientation and particle size distribution. The dp (superparamagnetic limit) value was calculated to be 7.5 nm. The Hc versus d plots at room temperature of BaFe12O19 (blue), SrFe12O19 (green), and CoFe2O4 (purple) are also shown.
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f2: Particle size dependence of the magnetic properties.(a) Magnetic hysteresis loops of S-1020, S-1044, S-1063, and S-1142 measured at 300 K with an illustration of the average particle size. (b) Hc value at 300 K with random orientation versus d plot. The red line is a guide for the eye, which was drawn based on the d dependence equation of Hc, taking into account the random orientation and particle size distribution. The dp (superparamagnetic limit) value was calculated to be 7.5 nm. The Hc versus d plots at room temperature of BaFe12O19 (blue), SrFe12O19 (green), and CoFe2O4 (purple) are also shown.

Mentions: The magnetic hysteresis loops of ε-Fe2O3 for S-951–S-1198 with random orientation at 300 K show that the Hc values are 0.4 kOe (S-951), 0.7 kOe (S-979), 2.1 kOe (S-1002), 3.4 kOe (S-1020), 4.7 kOe (S-1032), 8.3 kOe (S-1044), 11.9 kOe (S-1061), 12.8 kOe (S-1063), 17.3 kOe (S-1104), 20.3 kOe (S-1142), and 20.9 kOe (S-1198) (Fig. 2a, Supplementary Fig. S3). The magnetization versus temperature plots for S-951–S-1104 are shown in Supplementary Fig. S4. As shown in the Hc versus d plot of Fig. 2b, the Hc value decreases towards zero with decreasing d. In Fig. 2b, the particle size dependences of the Hc values of BaFe12O19, SrFe12O19, and CoFe2O4 reported so far are also plotted for reference (Supplementary Fig. S5).


Nanometer-size hard magnetic ferrite exhibiting high optical-transparency and nonlinear optical-magnetoelectric effect.

Ohkoshi S, Namai A, Imoto K, Yoshikiyo M, Tarora W, Nakagawa K, Komine M, Miyamoto Y, Nasu T, Oka S, Tokoro H - Sci Rep (2015)

Particle size dependence of the magnetic properties.(a) Magnetic hysteresis loops of S-1020, S-1044, S-1063, and S-1142 measured at 300 K with an illustration of the average particle size. (b) Hc value at 300 K with random orientation versus d plot. The red line is a guide for the eye, which was drawn based on the d dependence equation of Hc, taking into account the random orientation and particle size distribution. The dp (superparamagnetic limit) value was calculated to be 7.5 nm. The Hc versus d plots at room temperature of BaFe12O19 (blue), SrFe12O19 (green), and CoFe2O4 (purple) are also shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594123&req=5

f2: Particle size dependence of the magnetic properties.(a) Magnetic hysteresis loops of S-1020, S-1044, S-1063, and S-1142 measured at 300 K with an illustration of the average particle size. (b) Hc value at 300 K with random orientation versus d plot. The red line is a guide for the eye, which was drawn based on the d dependence equation of Hc, taking into account the random orientation and particle size distribution. The dp (superparamagnetic limit) value was calculated to be 7.5 nm. The Hc versus d plots at room temperature of BaFe12O19 (blue), SrFe12O19 (green), and CoFe2O4 (purple) are also shown.
Mentions: The magnetic hysteresis loops of ε-Fe2O3 for S-951–S-1198 with random orientation at 300 K show that the Hc values are 0.4 kOe (S-951), 0.7 kOe (S-979), 2.1 kOe (S-1002), 3.4 kOe (S-1020), 4.7 kOe (S-1032), 8.3 kOe (S-1044), 11.9 kOe (S-1061), 12.8 kOe (S-1063), 17.3 kOe (S-1104), 20.3 kOe (S-1142), and 20.9 kOe (S-1198) (Fig. 2a, Supplementary Fig. S3). The magnetization versus temperature plots for S-951–S-1104 are shown in Supplementary Fig. S4. As shown in the Hc versus d plot of Fig. 2b, the Hc value decreases towards zero with decreasing d. In Fig. 2b, the particle size dependences of the Hc values of BaFe12O19, SrFe12O19, and CoFe2O4 reported so far are also plotted for reference (Supplementary Fig. S5).

Bottom Line: Additionally, we have observed magnetization-induced second harmonic generation (MSHG).The nonlinear optical-magnetoelectric effect of the present polar magnetic nanocrystal was quite strong.These findings have been demonstrated in a simple iron oxide, which is highly significant from the viewpoints of economic cost and mass production.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

ABSTRACT
Development of nanometer-sized magnetic particles exhibiting a large coercive field (Hc) is in high demand for densification of magnetic recording. Herein, we report a single-nanosize (i.e., less than ten nanometers across) hard magnetic ferrite. This magnetic ferrite is composed of ε-Fe2O3, with a sufficiently high Hc value for magnetic recording systems and a remarkably high magnetic anisotropy constant of 7.7 × 10(6) erg cm(-3). For example, 8.2-nm nanoparticles have an Hc value of 5.2 kOe at room temperature. A colloidal solution of these nanoparticles possesses a light orange color due to a wide band gap of 2.9 eV (430 nm), indicating a possibility of transparent magnetic pigments. Additionally, we have observed magnetization-induced second harmonic generation (MSHG). The nonlinear optical-magnetoelectric effect of the present polar magnetic nanocrystal was quite strong. These findings have been demonstrated in a simple iron oxide, which is highly significant from the viewpoints of economic cost and mass production.

No MeSH data available.


Related in: MedlinePlus