### Session J40: QHE

11:15 AM–2:15 PM, Tuesday, March 6, 2007

Chair: Mansour Shayegan, Princeton University

Abstract ID: BAPS.2007.MAR.J40.2

### Abstract: J40.00002 : Anomalous Resistance Fluctuations in a Macroscopic 2DEG on a H-Si(111) Surface

11:27 AM–11:39 AM

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#### Authors:

Robert N. McFarland
(Laboratory for Physical Sciences, University of MD, College Park)

Kevin Eng
(Laboratory for Physical Sciences, University of MD, College Park)

Bruce E. Kane
(Laboratory for Physical Sciences, University of MD, College Park)

We report the experimental observation of large ($\sigma (R)/\left\langle R \right\rangle \sim$15{\%}) resistance fluctuations as a function of electron density for a high mobility 2DES induced on a free H-passivated Si(111) surface in the strongly metallic' regime. The observed fluctuations are reproducible and two orders of magnitude larger than the time-dependent noise. As the contact spacing ($\sim$1mm) is four orders of magnitude larger than the mean free path length ($\sim$100 nm), an explanation in terms of universal conductance fluctuations seems implausible. Because the dielectric is vacuum, the dominant scattering centers are located right at the surface. As discussed in [1], this 2DES has 6 unequally occupied valleys, which leads to an anisotropic longitudinal resistance. Interestingly, we note a strong anti-correlation between the fluctuations observed for orthogonal current directions. Furthermore, the fluctuations appear largely insensitive to small magnetic fields ($\vert$B$\vert <$ 2T). We present a systematic experimental characterization of this phenomenon, including temperature dependence (0.15 to 14K), I-V characteristics, and the response to perpendicular and parallel magnetic fields up to 12 T. [1] See talk `Experimental observation of six valleys and an anisotropic IQHE on H-Si(111) surfaces'' K. Eng \textit{et. al.}

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.MAR.J40.2