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- Berggren, Karl-Fredrik, 1937-, et al.
(author)
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Effects of electron interactions at crossings of Zeeman-split subbands in quantum wires
- 2005
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In: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 71:11, s. 115303-1-115303-5
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Journal article (peer-reviewed)abstract
- Recent experimental studies of Zeeman-split one-dimensional subbands in ballistic quantum wires in an in-plane magnetic field show that additional nonquantized conductance structures occur as subbands cross at low electron densities [A. C. Graham et al., Phys. Rev.Lett. 91, 136404 (2003)]. These structures are called 0.7 analogs. We analyze the experimental transconductance data within the Kohn-Sham spin-density-functional method, including exchange and correlation effects for an infinite split-gate quantum wire in a parallel, in-plane magnetic field B∥. Energy levels are found to rearrange abruptly as they cross due to polarization effects driven by exchange and Coulomb interactions. Experimental qualitative features are explained well by this model. ©2005 The American Physical Society.
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- Berggren, Karl-Fredrik, 1937-, et al.
(author)
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Electrical Resonance Circuits as Analogs to Quantum Mechanical Billiards
- 2006
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In: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 109, s. 33-42
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Journal article (peer-reviewed)abstract
- We propose that a two-dimensional electric network may be used for fundamental studies of wave function properties, transport, and related statistics. Using Kirchhoff 's current law and the jw-method we find that the network is analogous to a discretized Schrodinger equation for quantum billiards and clots. Thus the complex electric potentials play the role of quantum rnechanical wave functions.
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- Berggren, Karl-Fredrik, 1937-, et al.
(author)
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Electron transport and Nanomagnetism
- 2008
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In: Nordforsk Network in Nanospintronics Theory and Simulations,2008.
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Conference paper (other academic/artistic)abstract
- Electron states, local magnetization and conductance in realistic quantum point contacts (QPCs) with different geometry and applied gate voltages will be discussed for a model GaAs/AlGaAs device. Using the local spin density approximation (LSDA) we recover ferromagnetic spatially split solutions in the pinch-off regime as well as antisymmetric solutions that occur with increasing voltage. These kind of spin states, which may appear in a repeated fashion in the few electron regime, are precursors to an extended ferromagnetic state that may be associated with the 0.7 (2e2/h) conductance anomaly. As the length of the QPC increases, so does the spin polarization and the difference in conductance between up-spin and down-spin electrons, resulting in movement of 0.7 anomaly towards the value of 0.5 (2e2/h). Due to the strong ferromagnetic spin polarization in a long QPC it will effectively work as a spin filter which may be useful for spintronics application.
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