arXiv subjects
Publications and source records attributed to Keshav N. Shrivastava.
The High Landau level filling fractions 5/2, 7/3 and 8/3 are interpreted by using the angular momentum model. It is found that for the odd number of flux quanta, the quasiparticles called the ``composite fermions'' are fermions but for even number-, the quasiparticles are a mixture of bosons and fermions. Therefore, the theory of ``composite fermions'' is internally inconsistent.
We find that in the presence of an electric field there is an attractive intergrain interaction in superconductors which is small. When charge on the ball is permitted to vary with the ball radius, very large balls can be formed. The pairing energy makes the ball compact and hence reduces the size of the ball compared with the classical value. The ball radius depends on the gap of the superconductor due to Josephson tunneling.
We report that the rate of field sweep is important for the observation of the zeroes in the transverse resistivity in the quantum Hall effect. The resistivity also shows resonances at the nuclear magnetic resonance (NMR) frequencies when the r.f. coil is placed along the x direction. The relationship of the eigen values with the resistivity is pointed out which shows that even if the eigen values are largely corresponding to that of the single-particle, the plateau widths, shifts and shape require many-body interactions.
We introduce s.n where n is the unit vector in the direction of the radius vector and s is the spin, which along with the velocity forms a spin-orbit interaction of the order of v/c whereas the usual spin-orbit interaction is of the order of the square of v/c. The effective fractional charges obtained from this interaction are in good agreement with the experimental data of the quantum Hall effect. The energy of the system diverges as L tends to infinity indicating that there is a phase transformation at the half-filled Landau level.
The angular momentum model which couples the spin and charge is discussed as a possible theory of the quantum Hall effect. The high Landau level filling fractions 5/2, 7/3 and 8/3 are understood by this model. It is found that 7/3 and 8/3 are the particle-hole conjugates and 5/2 arises due to a limiting level at 1/2 with Landau level number n=5 which makes the fraction as 5/2.
Density-functional-theory calculations for the adsorption of molecular nitrogen on ruthenium surface are reported. It is found that nitrogen molecule is adsorbed while standing perpendicular to the triangular surface of ruthenium. The doping by K atoms favours the adsorption of molecular nitrogen. The calculation of the adsorption energy has also been performed on iron and osmium clusters which shows that ruthenium adsorbs better than iron or osmium. It is found that potential for atomic nitrogen is deeper and more stable than that of molecular nitrogen and hence atomic nitrogen is important for catalysis.