| 1. |
- Catani, J., et al.
(författare)
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Quantum dynamics of impurities in a one-dimensional Bose gas
- 2012
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 85:2
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Tidskriftsartikel (refereegranskat)abstract
- Using a species-selective dipole potential, we create initially localized impurities and investigate their interactions with a majority species of bosonic atoms in a one-dimensional configuration during expansion. We find an interaction-dependent amplitude reduction of the oscillation of the impurities’ size with no measurable frequency shift, and study it as a function of the interaction strength. We discuss possible theoretical interpretations of the data. We compare, in particular, with a polaronic mass shift model derived following Feynman variational approach.
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| 2. |
- Jayakumar, O. D., et al.
(författare)
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Enhancement of ferromagnetic properties in Zn0.95Co0.05O nanoparticles by indium codoping : An experimental and theoretical study
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:23, s. 232510-
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Tidskriftsartikel (refereegranskat)abstract
- Nanoparticles of Zn0.95-xCo0.05InxO (x = 0.0 to 0.07) were synthesized by the pyrolitic reaction of sol-gels obtained from respective metal precursors. X-ray diffraction and high-resolution transmission electron microscopy studies confirm the formation of impurity-free wurtzite type ZnO structure for all the compositions. While pristine ZnO is diamagnetic, Zn0.95Co0.05O nanoparticles show weak paramagnetic behavior at room temperature. When "In." is codoped with Co with x = 0.0 to 0.07 in Zn0.95-xCo0.05InxO, a systematic increase in magnetic moment is observed up to x = 0.07. First-principles modeling supports that the ferromagnetic phase become more favorable at higher indium doping concentrations.
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| 3. |
- Jayakumar, O. D., et al.
(författare)
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Experimental and theoretical investigations on magnetic behavior of (Al,Co) co-doped ZnO nanoparticles
- 2010
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 2:8, s. 1505-1511
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Tidskriftsartikel (refereegranskat)abstract
- We present the structural and magnetic properties of Zn0.95-xCo0.05AlxO (x = 0.0 to 0.1) nanoparticles, synthesized by a novel sol-gel route followed by pyrolysis. Powder X-ray diffraction data confirms the formation of a single phase wurtzite type ZnO structure for all the compositions. The Zn0.95Co0.05O nanoparticles show diamagnetic behavior at room temperature. However, when Al is co-doped with Co with x = 0.0 to 0.10 in Zn0.95-xCo0.05AlxO, a systematic increase in ferromagnetic moment is observed up to x = 0.07 at 300 K. Above x = 0.07 (e.g. for x = 0.10) a drastic decrease in ferromagnetic nature is observed which is concomitant with the segregation of poorly crystalline Al rich ZnO phase as evidenced from TEM studies. Theoretical studies using density functional calculations on Zn0.95-xCo0.05AlxO suggest that the partial occupancy of S2 states leads to an increased double exchange interaction favoring the ferromagnetic ground states. Such ferromagnetic interactions are favorable beyond a threshold limit. At a high level doping of Al, the exchange splitting is reduced, which suppresses the ferromagnetic ordering.
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| 4. |
- Slattery, DA, et al.
(författare)
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Neuropeptide S and anxiety
- 2012
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Ingår i: EUROPEAN NEUROPSYCHOPHARMACOLOGY. - 0924-977X. ; 22, s. S31-S32
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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