Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane Magnetoresistance in High-Mobility (100) Si Inversion Layers

Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane Magnetoresistance in High-Mobility (100) Si Inversion LayersComment: 1 page, submitted to PR

Nonlocal transport near the charge neutrality point in a two-dimensional electron-hole system

Nonlocal resistance is studied in a two-dimensional system with a simultaneous presence of electrons and holes in a 20 nm HgTe quantum well. A large nonlocal electric response is found near the charge neutrality point (CNP) in the presence of a perpendicular magnetic field. We attribute the observed nonlocality to the edge state transport via counter propagating chiral modes similar to the quantum spin Hall effect at zero magnetic field and graphene near Landau filling factor $\nu=0$Comment: 5 pages, 4 figure

Dilute electron gas near the metal-insulator transition in two dimensions

In recent years systematic experimental studies of the temperature dependence of the resistivity in a variety of dilute, ultra clean two dimensional electron/hole systems have revived the fundamental question of localization or, alternatively, the existence of a metal-insulator transition in the presence of strong electron-electron interactions in two dimensions. We argue that under the extreme conditions of ultra clean systems not only is the electron-electron interaction very strong but the role of other system specific properties are also enhanced. In particular, we emphasize the role of valleys in determining the transport properties of the dilute electron gas in silicon inversion layers (Si-MOSFETs). It is shown that for a high quality sample the temperature behavior of the resistivity in the region close to the critical region of the metal-insulator transition is well described by a renormalization group analysis of the interplay of interaction and disorder if the electron band is assumed to have two distinct valleys. The decrease in the resistivity up to five times has been captured in the correct temperature interval by this analysis, without involving any adjustable parameters. The considerable variance in the data obtained from different Si-MOSFET samples is attributed to the sample dependent scattering rate across the two valleys, presenting thereby with a possible explanation for the absence of universal behavior in Si-MOSFET samples of different quality

Pauli spin susceptibility of a strongly correlated two-dimensional electron liquid

Thermodynamic measurements reveal that the Pauli spin susceptibility of strongly correlated two-dimensional electrons in silicon grows critically at low electron densities - behavior that is characteristic of the existence of a phase transition.Comment: As publishe

A New Spin-Orbit Induced Universality Class in the Quantum Hall Regime ?

Using heuristic arguments and numerical simulations it is argued that the critical exponent $\nu$ describing the localization length divergence at the quantum Hall transition is modified in the presence of spin-orbit scattering with short range correlations. The exponent is very close to $\nu=4/3$, the percolation correlation length exponent, the prediction of a semi-classical argument. In addition, a region of weakly localized regime, where the localization length is exponentially large, is conjectured.Comment: 4 two-column pages including 4 eps figure

Tunneling into Ferromagnetic Quantum Hall States: Observation of a Spin Bottleneck

We explore the characteristics of equilibrium tunneling of electrons from a 3D electrode into a high mobility 2D electron system. For most 2D Landau level filling factors, we find that tunneling can be characterized by a single, well-defined tunneling rate. However, for spin-polarized quantum Hall states (nu = 1, 3 and 1/3) tunneling occurs at two distinct rates that differ by up to 2 orders of magnitude. The dependence of the two rates on temperature and tunnel barrier thickness suggests that slow in-plane spin relaxation creates a bottleneck for tunneling of electrons.Comment: 5 pages, 4 figures, submitted to PR

Sharp increase of the effective mass near the critical density in a metallic 2D electron system

We find that at intermediate temperatures, the metallic temperature dependence of the conductivity \sigma(T) of 2D electrons in silicon is described well by a recent interaction-based theory of Zala et al. (Phys. Rev. B 64, 214204 (2001)). The tendency of the slope d\sigma/dT to diverge near the critical electron density is in agreement with the previously suggested ferromagnetic instability in this electron system. Unexpectedly, it is found to originate from the sharp enhancement of the effective mass, while the effective Lande g factor remains nearly constant and close to its value in bulk silicon

Laparoscopic retropubic extraurethral adenomectomy

Introduction. Existing methods of surgical treatment of benign prostatic hyperplasia are accompanied by the frequent development of postoperative complications, such as urinary incontinence, retrograde ejaculation, and urethral strictures. The method of preserving the prostatic urethra has been developed for a long time. At present, it is possible to use the operation technique and perform laparoscopic urethral-sparing adenomectomy.Objective. To assess the possibility of performing extraurethral adenomectomy with prostatic urethral preservation using the laparoscopic approach, its advantages and disadvantages.Materials and methods. Based on St. Luke’s Simferopol сlinical Multidisciplinary Medical Center, 35 successful laparoscopic operations were performed to remove benign prostate hyperplasia with the prostatic urethra preservation. The features of the operation are laparoscopic access, a transverse section of the capsule, alternate isolation of adenomatous nodes while preserving the prostatic urethra on the catheter without replacing it during the operation, suturing the capsule with a decrease in space from the removed adenomatous nodes. Urethral preservation provided accelerated epithelialization of the defect, in the absence of the formation of a “prevesical” space.Results. After the operation, it is possible to turn off the urinary bladder irrigation system earlier (up to 4 – 6 hours after the operation) and early removal of the catheter after surgery (2 – 3 days). The hospital stay averaged 5.7 days. Urination was restored immediately after catheter removal in 92% of the patients. There were no elements of dysuria, particularly urinary incontinence. Prostate volume measured throughout transrectal ultrasound after operation was 20 – 24 cm³.Conclusion. The technique of retropubic extraurethral adenomectomy with prostatic urethral preservation can be performed in laparoscopic technique. The advantages are early activation of the patient and discharge from the hospital, early removal of the catheter with restoration of independent urination, absence of dysuria, urinary incontinence, and postoperative complications. The results of our study demonstrate the effectiveness of the laparoscopic extraurethral adenomectomy technique, the further development of this technique, and the possibility of its application in practice

Negative magneto-resistance of electron gas in a quantum well with parabolic potential

We have studied the electrical conductivity of the electron gas in parallel electric and magnetic fields directed along the plane of a parabolic quantum well (across the profile of the potential). We found a general expression for the electrical conductivity applicable for any magnitudes of the magnetic field and the degree of degeneration of the electron gas. A new mechanism of generation of the negative magnetoresistance has been revealed. It has been shown that in a parabolic quantum well with a non-degenerated electron gas the negative magnetoresistance results from spin splitting of the levels of the size quantization.Comment: 15 pages, 3 figure