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We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic…

The dynamic magnetic properties of Ni nanoparticles diluted in an amorphous SiO2 matrix prepared from a modified sol-gel method have been studied by the frequency f dependence of the ac magnetic susceptibility \c{hi}(T). For samples with…

Materials Science · Physics 2011-03-22 G. F. Goya , F. C. Fonseca , R. F. Jardim , R. Muccillo , N. L. V. Carreño , E. Longo , E. R. Leite

We prepared very high-coercivity cobalt ferrite nanoparticles using short-time high-energy mechanical milling. After the milling process, the coercivity of the nanoparticles reached 3.75 kOe - a value almost five times higher than that…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 E. F. Chagas , A. S. Ponce , R. J. Prado , G. M. Silva , J. Bettini , E. Baggio-Saitovitch

We study the magnetic properties of single crystals of rutile TiO2 implanted with cobalt for various fluences. The temperature variation of zero field cooled(ZFC) and field cooled (FC) magnetization shows a much higher blocking temperature…

Materials Science · Physics 2017-03-16 Shalik Ram Joshi , B. Padmanabhan , Anupama Chanda , N. Shukla , Vivek Malik , D. Kanjilal , Shikha Varma

We report detailed studies on non-equilibrium magnetic behavior of antiferromagnetic Co_3O_4 nanoparticles. Temperature and field dependence of magnetization, wait time dependence of magnetic relaxation (aging), memory effects and…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 Vijay Bisht , K. P. Rajeev

Co$_2$C nanoparticles (NPs) are amongst transition metal carbides whose magnetic properties have not been well explored. A recent study by Nirmal Roy et al. [1] showed that a collection of Co$_2$C NPs exhibit an exchange bias (EB) effect…

Strongly Correlated Electrons · Physics 2023-09-25 Nirmal Roy , P C Mahato , Suprotim Saha , M. Telling , J. S. Lord , D T Adroja , S. S. Banerjee

Recent work [1] demonstrated high coercivity and magnetic moment in cobalt carbide nanoparticle assemblies and explained the high coercivity from first principles in terms of the high magnetocrystalline anisotropy of the cobalt carbide…

Mesoscale and Nanoscale Physics · Physics 2018-09-26 Pallabi Sutradhar , Shiv N. Khanna , Jayasimha Atulasimha

We report about the magnetic properties of antiferromagnetic (AF) MnO nanoparticles (NPs) with different sizes (6-19nm). Using a combination of polarized neutron scattering and magnetometry we were able to resolve previously observed…

Mesoscale and Nanoscale Physics · Physics 2017-04-26 X. Sun , A. Klapper , Y. Su , K. Nemkovski , A. Wildes , H. Bauer , O. Köhler , A. Schilmann , W. Tremel , O. Petracic , Th. Brückel

We have studied the magnetic and power absorption properties of three samples of CoFe2O4 nanoparticles with sizes from 5 to 12 nm prepared by thermal decomposition of Fe (acac)3 and Co(acac)2 at high temperatures. The blocking temperatures…

Materials Science · Physics 2011-03-22 T. E. Torres , A. G. Roca , M. P. Morales , A. Ibarra , C. Marquina , M. R. Ibarra , G. F. Goya

Magnetic measurements up to 1000 K have been performed on hydrothermally synthesized $\alpha$-Fe$_{2}$O$_{3}$ nanoparticles (60 nm) using a Quantum Design vibrating sample magnetometer. A high vacuum environment (1$\times$10$^{-5}$ torr)…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Jun Wang , Wei Wu , Fan Zhao , Guo-meng Zhao

The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kAm-1, which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 muB that is…

Materials Science · Physics 2018-01-03 F. Eskandari , S. B. Porter , M. Venkatesan , P. Kameli , K. Rode , J. M. D. Coey

We report a systematic study on the structural and magnetic properties of Co_{x}Fe_{3-x}O_{4} magnetic nanoparticles with sizes between $5$ to $25$ nm, prepared by thermal decomposition of Fe(acac)_{3} and Co(acac)_{2}. The large…

Materials Science · Physics 2015-11-24 T. E. Torres , E. Lima , A. Mayoral , A. Ibarra , C. Marquina , M. R. Ibarra , G. F. Goya

Antiferromagnetic Bi_{2}Fe_{4}O_{9} (BFO), lightly substituted by cobalt is studied for magnetodielectricity. The substitution causes a substantial decrease in the Neel temperature (T_N) from 250 K (in parent sample, BFO) to 152 K (in 2% Co…

Materials Science · Physics 2017-09-19 S. R. Mohapatra , P. N. Vishwakarma , S. D. Kaushik , R. J. Choudhary , N. Mohapatra , A. K. Singh

We report detailed studies on magnetic properties of Co3O4 nanoparticles of average size 12.5 nm. Temperature and field dependence of magnetization, wait time dependence of magnetic relaxation (aging), memory effects and temperature…

Mesoscale and Nanoscale Physics · Physics 2010-09-03 Vijay Bisht , K. P. Rajeev

The temperature variation effect of shape anisotropy on the coercivity, HC(T), for the aligned Stoner-Wohlfarth (SW) soft ferromagnets, such as fcc Ni, fcc Co and bcc Fe, are investigated within the framework of Neel-Brown (N-B) analysis.…

Materials Science · Physics 2009-11-13 Lin He , Chinping Chen

We report specific heat ($C$) and magnetization ($M$) of single crystalline Ce$_4$Pt$_{12}$Sn$_{25}$ at temperature down to $\sim$50mK and in fields up to 3T. $C/T$ exhibits a sharp anomaly at 180mK, with a large $\Delta…

We study magnetic, transport and thermal properties of Cobalt carbide nanocomposite with a mixture of Co2C and Co3C phases in 1:1 ratio, with an average particle diameter of 40$\pm 15$ nm. We show that the behavior of the nanocomposite is…

Strongly Correlated Electrons · Physics 2020-03-31 Nirmal Roy , Arpita Sen , Prasenjit Sen , S. S. Banerjee

We report exchange bias (EB) in single-phase CoO nanoparticles, where two magnetic phases naturally emerge as the crystallite size decreases from 34.6 to 10.8 nm. The N\'eel temperature (TN) associated with antiferromagnetic ordering…

Mesoscale and Nanoscale Physics · Physics 2024-04-15 Vikash Sharma , Sudip Pal , Divya Sharma , Dinesh Kumar Shukla , Ram Janay Chaudhary , Gunadhor Singh Okram

Energy-efficient switching of nanoscale magnets requires the application of a time-varying magnetic field characterized by microwave frequency. At finite temperatures, even weak thermal fluctuations create perturbations in the magnetization…

Mesoscale and Nanoscale Physics · Physics 2023-12-19 Mohammad H. A. Badarneh , Grzegorz J. Kwiatkowski , Pavel F. Bessarab

We study the magnetic properties of spherical Co clusters with diameters between 0.8 nm and 5.4 nm (25 to 7500$ atoms) prepared by sequential sputtering of Co and Al2O3. The particle size distribution has been determined from the…

Materials Science · Physics 2009-11-07 F. Luis , J. M. Torres , L. M. Garcia , J. Bartolome , J. Stankiewicz , F. Petroff , F. Fettar , J. -L- Maurice , A. Vaures
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