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- Koksharov, Yu.A., et al.
(författare)
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Magnetostatic interactions in planar ring-like nanoparticle structures
- 2006
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 515, s. 731-734
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Tidskriftsartikel (refereegranskat)abstract
- Numerical calculations of equilibrium state energies and local magnetic fields in planar ring-like nanoparticle structures were performed. The dipole–dipole, Zeeman and magnetic anisotropy interactions were included into the model. The result of their competition depends on the value of the external magnetic field, magnetic parameters of an individual nanoparticle, size and shape of the structures. Flux-closed vortexes, single domain, two- domain ‘‘onion’’-like, ‘‘hedgehog’’-like and more complex spin structures can be realized. The critical field, providing a sharp transition from the flux-closed vortex to the ‘‘onion’’-like state, can be regulated by a variation of the particle magnetization and anisotropy constant, their easy directions, and particle space arrangement.
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- Liu, Ruisheng, et al.
(författare)
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Assembling ferromagnetic single-electron transistors by atomic force microscopy
- 2007
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Ingår i: Nanotechnology. - Bristol : Institute of Physics (IOP). - 0957-4484 .- 1361-6528. ; 18:5, s. 055302-
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the assembly of nanoscale ferromagnetic single-electron transistors using atomic force microscopy for imaging as well as for nanoscale manipulation. A single 30 nm Au disc, forming the central island of the transistor, is manipulated with angstrom precision into the gap between a plasma-oxidized Ni source and drain electrodes. The tunnel resistances can be tuned in real time during the device fabrication by repositioning the Au disc. Transport measurements reveal long-term stable single-electron transistor characteristics at 4.2 K. The well-controlled devices with very small central islands facilitate future in-depth studies of the interplay between Coulomb blockade, spin-dependent tunnelling and spin accumulation in ferromagnetic single-electron transistors at elevated temperatures.
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- Liu, Ruisheng, et al.
(författare)
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Large magnetoresistance in Co/Ni/Co ferromagnetic single electron transistors
- 2007
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Ingår i: Applied Physics Letters. - New York : American Institute of Physics. - 0003-6951 .- 1077-3118. ; 90:12, s. 123111-
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on magnetotransport investigations of nanoscaled ferromagnetic Co/Ni/Co single electron transistors. As a result of reduced size, the devices exhibit single electron transistor characteristics at 4.2 K. Magnetotransport measurements carried out at 1.8 K reveal tunneling magnetoresistance (TMR) traces with negative coercive fields, which the authors interpret in terms of a switching mechanism driven by the shape anisotropy of the central wirelike Ni island. A large TMR of about 18% is observed within a finite source-drain bias regime. The TMR decreases rapidly with increasing bias, which the authors tentatively attribute to excitation of magnons in the central island.
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- Liu, Ruisheng, et al.
(författare)
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Nanoscaled ferromagnetic single electron transistors
- 2007
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Ingår i: [Host publication title missing]. - Piscataway, N.J. : IEEE Press. ; 1-3, s. 420-423, s. 420-421
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report on a summary of fabricating and characterizing nanoscaled ferromagnetic single-electron transistors (F-SETs). One type of device is assembled with an atomic force microscope. A single 30 nm Au disc, forming the central island of the transistor, is manipulated with Angstrom precision into the gap between plasma oxidized Ni source and drain electrodes which are designed with different geometries to facilitate magnetic moment reversal at different magnetic fields. The tunnel resistances can be tuned in real-time during the device fabrication by re-positioning the An disc. A second type of device with Co electrodes and a central Au island is fabricated using a high-precision alignment procedure invoked during e-beam writing. Both devices exhibit single-electron transistor characteristics at 4.2K. From magnetotransport measurements carried out at 1.7K, we found that it is more efficient to realize spin injection and detection in Co/Au/Co devices fabricated with the second technique. A maximum TMR of about 4% was observed in these devices.
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