| 1. |
- Lidmar, Jack, 1968-, et al.
(författare)
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Critical properties of Bose-glass superconductors
- 1999
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 47:4
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Tidskriftsartikel (refereegranskat)abstract
- We study vortex lines in high-temperature superconductors with columnar defects produced by heavy-ion irradiation. We reconsider scaling theory for the Bose-glass transition with tilted magnetic fields, and propose, e.g. , a new scaling form for the shape of the Bose glass phase boundary, which is relevant for experiments. We also consider Monte Carlo simulations for a vortex model with a screened interaction. Critical exponents are determined from scaling analysis of Monte Carlo data for current-voltage characteristics and other quantities. The dynamic critical exponent is found to be z = 4.6 ± 0.3.
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| 2. |
- Lundin, Anders, et al.
(författare)
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Compressibility and Structure of C70
- 1995
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 30:8, s. 469-474
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Tidskriftsartikel (refereegranskat)abstract
- The compressibility of C70 has been investigated by means of direct piston and cylinder measurements in the temperature range 150 to 365 K and up to 1 GPa. At 296 and 343 K we find a very rapid change of volume with pressure below 0.15 GPa. We tentatively interpret this as a continuous molecular reorientation with pressure, probably resulting in a transformation from a mixture of face-centred cubic (f.c.c.) and rhombohedral (r.h.) phases to mainly pure r.h. phase. At 365 K as well as at 236 K and below we see no anomalies indicating any structural or rotational anomalies in the pressure range investigated. The zero-pressure bulk modulus decreases with increasing temperature, from 13.1 GPa at 185 K to 7.9 GPa at 365 K. Our volumetric measurements confirm a recently proposed phase diagram for C70.
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| 3. |
- Moret, Roger, et al.
(författare)
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First X-ray diffraction analysis of pressure polymerized C60 single crystals
- 1997
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 40:1, s. 55-60
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that C60 single crystals can be polymerized under relatively modest pressure-temperature conditions. The resulting single crystals exhibit long-range order and they are made up of 12 orientation variants. The structure is orthorhombic with a short intermolecular distance along the chains (9.14 Å), characteristic of covalent bonding. We propose a structural mechanism for the polymerization of fullerene-based compounds; it involves a shift of one of the (111) cubic planes together with a shortening of the (111) spacing. The configuration of the polymer chains presents interesting relations with that found in the A1C60 polymer compounds.
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| 4. |
- Nilsson, Thomas, 1965, et al.
(författare)
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Neutron Momentum Distributions from Core Break-up Reactions of Halo Nuclei
- 1995
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Ingår i: Europhysics Letters. - 0295-5075 .- 1286-4854. ; 30:1, s. 19-24
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Tidskriftsartikel (refereegranskat)abstract
- Neutron angular distributions from violent break-up reactions of Li-11 and Be-11 have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles.
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| 5. |
- Nyeanchi, Emmanuel B., et al.
(författare)
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Ferromagnetic ground state in La0.5Ca0.5MnO3 thin films
- 1999
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Ingår i: Europhysics letters. - : Institute of Physics (IOP). - 0295-5075 .- 1286-4854. ; 48:2, s. 228-232
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Tidskriftsartikel (refereegranskat)abstract
- Resistivity and magnetisation measurements were done with bulk and thin-film samples of La0.05Ca0.05MnO3. Bulk samples showed an antiferromagnetic insulating ground state as expected for this composition, whereas thin films demonstrated a ferromagnetic metallic ground state. This effect is attributed to the film adhesion to the substrate which prevents the lattice distortions necessary for the charge and antiferromagnetic ordering that occur in the bulk samples.
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