| 61. |
- Stensson, Annika, et al.
(författare)
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Industry demands on vehicle development - methods and tools
- 1999
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 33:Suppl 1, s. 202-213
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Tidskriftsartikel (refereegranskat)abstract
- A very important goal of mechatronics in system development is the integration of mechanical, electronic and software subsystems in order to increase functionality, minimize weight, and reduce production costs. In this work, industry demands on methods and tools for mechatronic vehicle development are addressed from the current product development in industry. The development of a mechatronic car door concept and dynamic stability control are used as examples to identify strong and weak parts of the current processes. Railway vehicle development aspects are also discussed. It is shown that a very important aspect for a successful mechatronic design is co-operation in an interdisciplinary design team. In terms of design methodology, the systematic identification of mechatronic potential based on function analysis is a main issue. Computer tools and technology for concept simulation, co-simulation, managing of models with different complexity as well as model exchange are identified as important demands for future effective development of mechatronic vehicles.
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| 62. |
- Stoll, O. M., et al.
(författare)
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Hysteresis and fractional matching in thin Nb films with rectangular arrays of nanoscaled magnetic dots
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 65:10
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the periodic pinning of magnetic flux quanta in thin Nb films with rectangular arrays of magnetic dots. In this type of pinning geometry, a change in the periodicity and shape of the minima in the magnetoresistance occurs for magnetic fields exceeding a certain threshold value. This was explained recently in terms of a reconfiguration transition of the vortex lattice due to an increasing vortex-vortex interaction with increasing magnetic field. In this picture the dominating elastic energy at high fields forces the vortex lattice to form a square symmetry, rather than being commensurate with the rectangular geometry of the pinning array. In this paper we present a comparative study of rectangular arrays with Ni dots, Co dots, and holes. In the magnetic dot arrays we found a strong fractional matching effect up to the second-order matching field. In contrast, no clear fractional matching is seen after the reconfiguration. Additionally, we discover the existence of hysteresis in the magnetoresistance in the crossover between the low- and high-field regimes. We find evidence that this effect is correlated with the reconfiguration phenomenon rather than to the magnetic state of the dots. The temperature and angular dependences of the effect are measured, and possible models are discussed to explain this behavior.
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| 63. |
- Thees, Maximilian, et al.
(författare)
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Imaging the itinerant-to-localized transmutation of electrons across the metal-to-insulator transition in V2O3
- 2021
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:45
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Tidskriftsartikel (refereegranskat)abstract
- In solids, strong repulsion between electrons can inhibit their movement and result in a “Mott” metal-to-insulator transition (MIT), a fundamental phenomenon whose understanding has remained a challenge for over 50 years. A key issue is how the wave-like itinerant electrons change into a localized-like state due to increased interactions. However, observing the MIT in terms of the energy- and momentum-resolved electronic structure of the system, the only direct way to probe both itinerant and localized states, has been elusive. Here we show, using angle-resolved photoemission spectroscopy (ARPES), that in V2O3, the temperature-induced MIT is characterized by the progressive disappearance of its itinerant conduction band, without any change in its energy-momentum dispersion, and the simultaneous shift to larger binding energies of a quasi-localized state initially located near the Fermi level.
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| 64. |
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| 65. |
- Åkerman, Johan, et al.
(författare)
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Criteria for ferromagnetic-insulator-ferromagnetic tunneling
- 2002
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Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853 .- 1873-4766. ; 240:03-jan, s. 86-91
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Tidskriftsartikel (refereegranskat)abstract
- The Rowell criteria, commonly used to identify tunneling in magnetic tunnel junctions (MTJ), are scrutinized. While neither the exponential-thickness dependence of the conductivity nor fits of non-linear transport data are found to be reliable tunneling criteria, the temperature-dependent conductivity does remain a solid criterion. Based on experimental studies of the bias and temperature-dependent resistance and magnetoresistance of MTJs, with and without shorted barriers, a new set of criteria is formulated.
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| 66. |
- Åkerman, Johan, et al.
(författare)
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Origin of temperature dependence in tunneling magnetoresistance
- 2003
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 63:1, s. 104-110
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Tidskriftsartikel (refereegranskat)abstract
- We present detailed measurements of the differential resistance (dV/dI) of state-of-the-art FM/AlOx/FM magnetic tunnel junctions (MTJ) as a function of applied bias and temperature. Temperature effects are particularly significant in physical quantities involving narrow features such as those at low-voltage bias. We show that the temperature evolution of the tunneling characteristics and, in particular, the pronounced rounding of the dV/dI curves with increasing temperature can be well explained by thermal smearing of the tunneling electron energy distribution.
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| 67. |
- Åkerman, Johan, et al.
(författare)
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Tunneling criteria for magnetic-insulator-magnetic structures
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:19, s. 3104-3106
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Tidskriftsartikel (refereegranskat)abstract
- The bias and temperature dependent resistance and magnetoresistance of magnetic tunnel junctions with and without intentional shorts through the insulating barrier were studied. Based on the experimental results, a set of quality criteria was formulated that enables the identification of barrier shorts. While the temperature and bias dependencies of the junction resistance and of the fitted barrier parameters are very sensitive to the presence of such shorts, the same dependencies of the magnetoresistance are surprisingly insensitive. Finally, junctions with a shorted barrier exhibit a dramatic increase in noise level and junction instability.
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