Berlin 2005 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
TT: Tiefe Temperaturen
TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique
TT 16.23: Poster
Samstag, 5. März 2005, 11:00–16:30, Poster TU C
Magnetic field dependence of the electronic phase coherence length of diffusive nanowires with magnetic impurities — •Christian Schirm1, Elke Scheer1, Christian Paschke2, Christoph Sürgers2, and Hilbert v. Löhneysen2 — 1Fachbereich Physik, Universität Konstanz, D-78464 Konstanz — 2Physikalisches Institut and DFG Center for Functional Nanostructures (CFN), Universität Karlsruhe, D-76128 Karlsruhe
For the study of the electronic phase coherence length lϕ of diffusive metal structures at very low temperatures, Mohanty et al. [1] propose to investigate the conductance fluctuations (CF) at high magnetic fields. The authors claim that the possible presence of small amounts of magnetic impurities should be detectable by analyzing the field dependence of the fluctuations. In [2] the CF of diffusive Cu nanowires, intentionally contaminated with Mn impurities in the ppm range, were investigated. We had observed a complex field and concentration dependence of lϕ. We re-evaluated the data of [2] with a refined numerical treatment. The influence of the signal to noise ratio (SNR) of the conductance measurements on the determination of lϕ is discussed. Although the SNR in [2] is of the same order or better than in [1] we obtain a wide range of possible values for lϕ depending on the treatment of the background and other numerical or physical parameters. Thus, the absence of a magnetic field dependence of lϕ cannot be taken as evidence against the presence of magnetic impurities limiting lϕ for T→ 0.
P. Mohanty et al., Phys. Rev. Lett. 91, 066604 (2003)
H. v. Löhneysen et al., Physica B 284-288, 1858 (2000)