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Controlling exchange bias in Fe3O4/FeO composite particles prepared by pulsed laser irradiation.

Swiatkowska-Warkocka Z, Kawaguchi K, Wang H, Katou Y, Koshizaki N - Nanoscale Res Lett (2011)

Bottom Line: Through tuning the laser fluence, the Fe3O4/FeO phase ratio can be precisely controlled, and the magnetic properties of final products can also be regulated.This work presents a successful example of the fabrication of ferro (ferri) (FM)/antiferromagnetic (AFM) systems with high chemical stability.The results show this novel simple method as widely extendable to various FM/AFM nanocomposite systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565 Ibaraki, Japan. zaneta.swiatkowska@aist.go.jp.

ABSTRACT
Spherical iron oxide nanocomposite particles composed of magnetite and wustite have been successfully synthesized using a novel method of pulsed laser irradiation in ethyl acetate. Both the size and the composition of nanocomposite particles are controlled by laser irradiation condition. Through tuning the laser fluence, the Fe3O4/FeO phase ratio can be precisely controlled, and the magnetic properties of final products can also be regulated. This work presents a successful example of the fabrication of ferro (ferri) (FM)/antiferromagnetic (AFM) systems with high chemical stability. The results show this novel simple method as widely extendable to various FM/AFM nanocomposite systems.

No MeSH data available.


Related in: MedlinePlus

Magnetic hysteresis loops for the samples with 75% of FeO. Coercivity Hc and exchange bias Hexch of Fe3O4/FeO composite particles as a function of temperature.
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Figure 7: Magnetic hysteresis loops for the samples with 75% of FeO. Coercivity Hc and exchange bias Hexch of Fe3O4/FeO composite particles as a function of temperature.

Mentions: In order to explore the origin of Hexch, the temperature dependence of Hexch obtained from magnetic hysteresis loops for the samples with 75% of FeO were also studied. The sample was first cooled down from 300 K to the measuring temperature under a magnetic field of 50 kOe, and then the loop was measured. This process was repeated for every measuring temperature. As presented in Figure 7, Hexch decreases with the temperature increase and appears to vanish at about 190 K. This blocking temperature is equal to the Neel temperature (TN) of FeO (for FeO TN = 198 K [24]). At a higher temperature, the coupling between FM and AFM regions is weakened by thermal disturbance. As the temperature decreases, the exchange interaction between the above two types of regions becomes stronger, resulting in the loop shift which becomes more prominent at a lower temperature. However, coercivity Hc does not decrease to zero and its value approaches to the intrinsic Hc of particles without exchange bias.


Controlling exchange bias in Fe3O4/FeO composite particles prepared by pulsed laser irradiation.

Swiatkowska-Warkocka Z, Kawaguchi K, Wang H, Katou Y, Koshizaki N - Nanoscale Res Lett (2011)

Magnetic hysteresis loops for the samples with 75% of FeO. Coercivity Hc and exchange bias Hexch of Fe3O4/FeO composite particles as a function of temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211284&req=5

Figure 7: Magnetic hysteresis loops for the samples with 75% of FeO. Coercivity Hc and exchange bias Hexch of Fe3O4/FeO composite particles as a function of temperature.
Mentions: In order to explore the origin of Hexch, the temperature dependence of Hexch obtained from magnetic hysteresis loops for the samples with 75% of FeO were also studied. The sample was first cooled down from 300 K to the measuring temperature under a magnetic field of 50 kOe, and then the loop was measured. This process was repeated for every measuring temperature. As presented in Figure 7, Hexch decreases with the temperature increase and appears to vanish at about 190 K. This blocking temperature is equal to the Neel temperature (TN) of FeO (for FeO TN = 198 K [24]). At a higher temperature, the coupling between FM and AFM regions is weakened by thermal disturbance. As the temperature decreases, the exchange interaction between the above two types of regions becomes stronger, resulting in the loop shift which becomes more prominent at a lower temperature. However, coercivity Hc does not decrease to zero and its value approaches to the intrinsic Hc of particles without exchange bias.

Bottom Line: Through tuning the laser fluence, the Fe3O4/FeO phase ratio can be precisely controlled, and the magnetic properties of final products can also be regulated.This work presents a successful example of the fabrication of ferro (ferri) (FM)/antiferromagnetic (AFM) systems with high chemical stability.The results show this novel simple method as widely extendable to various FM/AFM nanocomposite systems.

View Article: PubMed Central - HTML - PubMed

Affiliation: Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, 305-8565 Ibaraki, Japan. zaneta.swiatkowska@aist.go.jp.

ABSTRACT
Spherical iron oxide nanocomposite particles composed of magnetite and wustite have been successfully synthesized using a novel method of pulsed laser irradiation in ethyl acetate. Both the size and the composition of nanocomposite particles are controlled by laser irradiation condition. Through tuning the laser fluence, the Fe3O4/FeO phase ratio can be precisely controlled, and the magnetic properties of final products can also be regulated. This work presents a successful example of the fabrication of ferro (ferri) (FM)/antiferromagnetic (AFM) systems with high chemical stability. The results show this novel simple method as widely extendable to various FM/AFM nanocomposite systems.

No MeSH data available.


Related in: MedlinePlus