Shubnikov-de Haas oscillations in p-type inversion layers on n-type silicon

Surface Shubnikov-de Haas oscillations have been measured in p-type channels of (110) silicon field effect transitors between 1.4 and 4.2 K in magnetic fields up to 10 Tesla. Two electric subbands were revealed and the effective masses of the holes in both bands could be determined. For one subband the dependence of the mass on the surface electric field was investigated. At low gate voltages the g-factor of the holes was measured from the spin splitting of the Landau-levels.     

The investigation of LRA fission of235U by non-shielded semiconductor telescope

The LRA particles energy spectrum from ternary thermal neutron induced fission of²³⁵U has been measured. A nonshielded semiconductor telescope technique has been used. The experimental spectrum has been fitted by the Gaussian distribution with average alpha energy of 15·65 ±0·09 MeV and full width at half maximum of 9·56±0.10 MeV.     

Surface quantum oscillations in n-type (100) silicon inversion layers on sapphire

Measurements of Shubnikov-de Haas oscillations in (100) Si/($\text{1}$012)Al₂O₃ MOSFET's were performed in magnetic fields up to 10 Tesla for different tilt angles between the magnetic field direction and the surface normal. The experimental results show that the lowest electric subband in this system is twofold degenerate and is formed by the “heavy” cyclotron mass valleys. This can be explained by a large lateral stress present in the SOS (silicon on sapphire) system.     

New type of B-periodic magneto-oscillations in a two-dimensional electron system induced by microwave irradiation

We observe a new type of magneto-oscillations in the photovoltage and the longitudinal resistance of a two-dimensional electron system. The oscillations are induced by microwave radiation and are periodic in magnetic field. The period is determined by the microwave frequency, the electron density, and the distance between potential probes. The phenomenon is accounted for by interference of coherently excited edge magnetoplasmons in the contact regions and offers perspectives for developing new tunable microwave and terahertz detection schemes and spectroscopic techniques.     

Absence of odd-even parity behavior for Kondo resonances in quantum dots

Zero-bias anomalies in the conductance through quantum dots have recently been identified as Kondo resonances and explained in terms of the Anderson impurity model. The effect requires a degeneracy and it has been proposed that this should occur for odd electron numbers on the dot. In this paper we present data, obtained on a split-gate quantum dot with a small number of electrons, which are in disagreement with this expectation. The mapping of the Anderson model on the quantum dot is discussed in terms of an interacting N electron system demonstrating why this expectation can fail.     

Spontaneous emergence of angular momentum josephson oscillations in coupled annular bose-einstein condensates

We investigate the nonlinear dynamics of two coupled annular Bose-Einstein condensates (BECs). For certain values of the coupling strength the nonrotating state with uniform density is unstable with respect to fluctuations in the higher angular momentum modes. The Bogoliubov spectrum possesses two branches, one of which exhibits distinct regions of instability enabling one to selectively occupy certain angular momentum modes. For sufficiently long evolution times, angular momentum Josephson oscillations spontaneously appear, breaking the initial chiral symmetry of the BECs.     

镍钼杂多酸制备NiMo/γ-Al2O3催化剂及硼、钴或镍改性氧化铝的影响（英文）

A hydrotreating NiMo/γ-Al2O3 catalyst(12 wt% Mo and 1.1 wt% Ni) was prepared by impregnation of the support with the Anderson-type heteropolyoxomolybdate(NH4)4Ni(OH)6Mo6O18.Before impregnation of the support,it was modified with an aqueous solution of H3BO3,Co(NO3)2,or Ni(NO3)2.The catalysts were investigated using N2 adsorption,O2 chemisorption,X-ray diffraction,UV-Vis spectroscopy,Fourier transform infrared spectroscopy,temperature-programmed reduction,temperature-programmed desorption,and X-ray photoelectron spectroscopy.The addition of Co,Ni,or B influenced the Al2O3 phase composition and gave increased catalytic activity for 1-benzothiophene hydrodesulfurization(HDS).X-ray photoelectron spectroscopy confirmed that the prior loading of Ni,Co or B increased the degree of sulfidation of the NiMo/γ-Al2O3 catalysts.The highest HDS activity was observed with the NiMo/γ-Al2O3 catalyst with prior loaded Ni.     

Observation of a hybridization gap in cyclotron resonance spectra of semimetallic InAs/GaSb quantum wells

Splitting of the cyclotron resonance (CR) line is observed in the electron CR spectra of InAs/GaSb heterostructures containing tunneling-coupled electron and hole layers. This splitting is interpreted to be a manifestation of a hybridization gap arising as a result of anticrossing of the Landau levels of electrons and holes when their wave functions overlap. The energy splitting of the CR lines is correlated with the magnitude of the overlap and agrees with theoretical estimates of the hybridization gap width. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 4, 313–317 (25 February 1999)