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Effects of exchange and electron correlation on conductance and nanomagnetism in ballistic semiconductor quantum point contacts
Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
2002 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 66, no 8Article in journal (Refereed) Published
Abstract [en]

The spontaneous magnetization of a quantum point contact (QPC) formed between two large quantum dots by a lateral confinement of a high-mobility two-dimensional electron gas is studied for a realistic GaAs/AlxGa1-xAs heterostructure. The model of the device incorporates the contributions from a patterned gate, doping, surface states, and mirror charges. To explore the magnetic properties, the Kohn-Sham local spin-density formalism is used with exchange and correlation potentials that allows for local spin polarization. Exchange is the dominant mechanism behind local magnetization within the QPC, while the correlation part is less prominent. However, the correlation potential gives rise to an important correction in the QPC potential. Below the first conduction plateau we thus find a magnetized regime corresponding approximately to a single electron spin. Using an approximate separable saddle potential we compute the conductance and recover the so-called similar to0.7 (2e(2)/h) conduction anomaly plus an additional anomaly at similar to0.4 (2e(2)/h) below which the magnetization collapses.

Place, publisher, year, edition, pages
2002. Vol. 66, no 8
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-47854DOI: 10.1103/PhysRevB.66.085323OAI: diva2:268750
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2011-01-13

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Berggren, Karl-Fredrik
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The Institute of TechnologyTheoretical Physics
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