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Full-Text Articles in Physics
Reply To Comment On Origin Of Surface Canting Within Fe3o4 Nanoparticles, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, Yumi Ijiri, K. Hasz, J.J. Rhyne, S.A. Majetich
Reply To Comment On Origin Of Surface Canting Within Fe3o4 Nanoparticles, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, Yumi Ijiri, K. Hasz, J.J. Rhyne, S.A. Majetich
Faculty & Staff Scholarship
No abstract provided.
Particle Moment Canting In Cofe2o4 Nanoparticles, K. Hasz, Yumi Ijiri, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, S. Oberdick, S.A. Majetich
Particle Moment Canting In Cofe2o4 Nanoparticles, K. Hasz, Yumi Ijiri, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, S. Oberdick, S.A. Majetich
Faculty & Staff Scholarship
Polarization-analyzed small-angle neutron scattering methods are used to determine the spin morphology in high crystalline anisotropy, 11 nm diameter CoFe2O4 nanoparticle assemblies with randomly oriented easy axes. In moderate to high magnetic fields, the nanoparticles adopt a uniformly canted structure, rather than forming domains, shells, or other arrangements. The observed canting angles agree quantitatively with those predicted from an energy model dominated by Zeeman and anisotropy competition, with implications for the technological use of such nanoparticles.
Inverted Linear Halbach Array For Separation Of Magnetic Nanoparticles, Yumi Ijiri, Chetan Poudel, P. Stephen Williams, Lee R. Moore, Toru Orita, Maciej Zborowski
Inverted Linear Halbach Array For Separation Of Magnetic Nanoparticles, Yumi Ijiri, Chetan Poudel, P. Stephen Williams, Lee R. Moore, Toru Orita, Maciej Zborowski
Faculty & Staff Scholarship
A linear array of Nd-Fe-B magnets has been designed and constructed in an inverted Halbach configuration for use in separating magnetic nanoparticles. The array provides a large region of relatively low magnetic field, yet high magnetic field gradient in agreement with finite element modeling calculations. The magnet assembly has been combined with a flow channel for magnetic nanoparticle suspensions, such that for an appropriate distance away from the assembly, nanoparticles of higher moment aggregate and accumulate against the channel wall, with lower moment nanoparticles flowing unaffected. The device is demonstrated for iron oxide nanoparticles with diameters of ~5 and 20 …
Velocity-Selective Direct Frequency-Comb Spectroscopy Of Atomic Vapors, Jason E. Stalnaker, S. L. Chen, M. E. Rowan, K. Nguyen, T. Pradhananga, C. A. Palm, Derek F. Jackson Kimball
Velocity-Selective Direct Frequency-Comb Spectroscopy Of Atomic Vapors, Jason E. Stalnaker, S. L. Chen, M. E. Rowan, K. Nguyen, T. Pradhananga, C. A. Palm, Derek F. Jackson Kimball
Faculty & Staff Scholarship
We present an experimental and theoretical investigation of two-photon direct frequency-comb spectroscopy performed through velocity-selective excitation. In particular, we explore the effect of repetition rate on the [formula] two-photon transitions excited in a rubidium atomic vapor cell. The transitions occur via stepwise excitation through the [formula] states by use of the direct output of an optical frequency comb. Experiments were performed with two different frequency combs, one with a repetition rate of [formula] MHz and one with a repetition rate of [formula] MHz. The experimental spectra are compared to each other and to a theoretical model.
Polarization-Analyzed Small-Angle Neutron Scattering. Ii. Mathematical Angular Analysis, Kathryn L. Krycka, Julie A. Borchers, Yumi Ijiri, R.A. Booth, S.A. Majetich
Polarization-Analyzed Small-Angle Neutron Scattering. Ii. Mathematical Angular Analysis, Kathryn L. Krycka, Julie A. Borchers, Yumi Ijiri, R.A. Booth, S.A. Majetich
Faculty & Staff Scholarship
Polarization-analyzed small-angle neutron scattering (SANS) is a powerful tool for the study of magnetic morphology with directional sensitivity. Building upon polarized scattering theory, this article presents simplified procedures for the reduction of longitudinally polarized SANS into terms of the three mutually orthogonal magnetic scattering contributions plus a structural contribution. Special emphasis is given to the treatment of anisotropic systems. The meaning and significance of scattering interferences between nuclear and magnetic scattering and between the scattering from magnetic moments projected onto distinct orthogonal axes are discussed in detail. Concise tables summarize the algorithms derived for the most commonly encountered conditions. These …
Core-Shell Magnetic Morphology Of Structurally Uniform Magnetite Nanoparticles, Kathryn L. Krycka, R.A. Booth, C.R. Hogg, Y. Ijiri, Julie A. Borchers, W.C. Chen, S.M. Watson, M. Laver, T.R. Gentile, Liv R. Dedon
Core-Shell Magnetic Morphology Of Structurally Uniform Magnetite Nanoparticles, Kathryn L. Krycka, R.A. Booth, C.R. Hogg, Y. Ijiri, Julie A. Borchers, W.C. Chen, S.M. Watson, M. Laver, T.R. Gentile, Liv R. Dedon
Faculty & Staff Scholarship
A new development in small-angle neutron scattering with polarization analysis allows us to directly extract the average spatial distributions of magnetic moments and their correlations with three-dimensional directional sensitivity in any magnetic field. Applied to a collection of spherical magnetite nanoparticles 9.0 nm in diameter, this enhanced method reveals uniformly canted, magnetically active shells in a nominally saturating field of 1.2 T. The shell thickness depends on temperature, and it disappears altogether when the external field is removed, confirming that these canted nanoparticle shells are magnetic, rather than structural, in origin.
Internal Magnetic Structure Of Magnetite Nanoparticles At Low Temperature, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, C.R. Hogg, Yumi Ijiri, W.C. Chen, S.M. Watson, M. Laver, T.R. Gentile, S. Harris
Internal Magnetic Structure Of Magnetite Nanoparticles At Low Temperature, Kathryn L. Krycka, Julie A. Borchers, R.A. Booth, C.R. Hogg, Yumi Ijiri, W.C. Chen, S.M. Watson, M. Laver, T.R. Gentile, S. Harris
Faculty & Staff Scholarship
Small-angle neutron scattering with polarization analysis reveals that Fe3O4 nanoparticles with 90 Å diameters have ferrimagnetic moments significantly reduced from that of bulk Fe3O4 at 10 K, nominal saturation. Combined with previous results for an equivalent applied field at 200 K, a core-disordered shell picture of a spatially reduced ferrimagnetic core emerges, even well below the bulk blocking temperature. Zero-field cooling suggests that this magnetic morphology may be intrinsic to the nanoparticle, rather than field induced, at 10 K.