C.T. Seip

Publications (3)2.73 Total impact

• Article: Magnetic properties of a series of ferrite nanoparticles synthesized in reverse micelles

  C.T. Seip, E.E. Carpenter, C.J. O'Connor, V.T. John, Sichu Li
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  ABSTRACT: Nanoscale particles of the general formula MFe₂O₄ (M=Co, Mn, Fe) were synthesized in reverse micelles of twin-tailed anionic bis(2-ethylhexyl) sodium sulfosuccinate (AOT) in isooctane. The size of the particles was controlled by adjusting the AOT/water molar ratio. Particle sizes were confirmed using XRD and uniformity was determined by SEM. Magnetic measurements, carried out using a SQUID Susceptometer, indicated superparamagnetic behavior. FC and ZFC demagnetization experiments indicate blocking temperatures of 46 K, 30 K, and 7 K for for MFe₂O₄ M=Co, Mn, Fe respectively. Below blocking temperatures, the nanoparticles demonstrate hysteresis with coercivities of H_c=6000G, 3800G, and 500G for the Co, Mn, and Fe ferrites
  IEEE Transactions on Magnetics 08/1998; · 1.36 Impact Factor
• Article: Magnetotransport and magnetism in granular EuS-Co and EuS-Ag nanocomposites prepared by mechanical alloying

  C.E. O'Connor, Li Feng, C.T. Seip, Jinke Tang
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  ABSTRACT: Magnetic and magnetotransport properties have been studied in nanocomposites (EuS)-Co and (EuS)-Ag prepared by mechanical alloying. For (EuS)₇₀Co₃₀, the large negative magnetoresistance (~50%) found at 20 K, just above the Curie temperature (T_c) of EuS, arises from the suppression of spin fluctuation in EuS. Below T_c, the positive magnetoresistance (~15%), which is uncharacteristic of ferromagnetic semiconductors, is probably due to defect-induced magnetic fluctuation. On the other hand, (EuS)₇₀Ag₃₀, where nonmagnetic silver replaces cobalt, exhibits negative magnetoresistance below T_c, which is possibly related to the spin dependent scattering commonly seen in GMR materials. While (EuS)₇₀Co₃₀ shows semiconducting conductivity, (EuS)₇₀Ag₃₀ is metallic. Reentrant spin glass behavior has been observed in EuS-Ag system, where the rise of antiferromagnetic coupling is due to the defects and disorder caused by mechanical milling
  IEEE Transactions on Magnetics 08/1998; · 1.36 Impact Factor
• Conference Proceeding: Magnetic Properties of Cobalt and Manganese Ferrite Nanoparticles Synthesized Reverse Micelles

  E.E. Carpenter, C.T. Seip, C.J. O'Connor
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  ABSTRACT: Not Available
  MMM-Intermag Conference, 1998. Abstracts., The 7th Joint; 02/1998