Application of Positron Annihilation Spectroscopy Studies of Bismuth and Subsurface Zone Induced by Sliding

The positron annihilation, experimental and theoretical results obtained for bismuth are presented, mainly concerning the open volume defects created during compression and dry sliding. Positron lifetime in vacancy clusters increases with the size of the cluster; however, it saturates at the value of about 0.42 ns already for six vacancies in a cluster. Similar values were resolved in the positron lifetime spectra of bismuth samples exposed to dry sliding. Detection of the subsurface zone in bismuth exposed to dry sliding reveals exponential decay of vacancy clusters concentration with the depth increase from the worn surface. The high strain of about 70% was evaluated in the layer adjoined the worn surface The temperature of recrystallization obtained from the isochronal measurements of annihilation line shape parameter was equal about 90°C, and the activation energy for grain migration is about 0.84 ± 0.11 eV

Electrons as quasi-bosons in magnetic white dwarfs

A white dwarf star achieves its equilibrium from the balancing of the gravitational compression against the Fermi degeneracy pressure of the electron gas. In field theory there are examples (e.g. the monopole-charge system) where a strong magnetic field can transform a boson into a fermion or a fermion into a boson. In some condensed matter systems (e.g. fractional quantum Hall systems) a strong magnetic field can transform electrons into effective fermions, or effective anyons. Based on these examples we investigate the possibility that the strong magnetic fields of some white dwarfs may transform some fraction of the electrons into effective bosons. This could have consequences for the structure of highly magnetized white dwarfs. It would alter the mass-radius relationship, and in certain instances one could envision a scenario where a white dwarf below the Chandrasekhar limit could nevertheless collapse into a neutron star due to a weakening of the electron degeneracy pressure. In addition the transformation of electrons into effective bosons could result in the electrons Bose condensing, which could speed up the cooling rate of white dwarfs.Comment: 10 pages. To be published IJMP

Electromagnetic field angular momentum in condensed matter systems

Various electromagnetic systems can carry an angular momentum in their {\bf E} and {\bf B} fields. The electromagnetic field angular momentum (EMAM) of these systems can combine with the spin angular momentum to give composite fermions or composite bosons. In this paper we examine the possiblity that an EMAM could provide an explanation of the fractional quantum Hall effect (FQHE) which is complimentary to the Chern-Simons explanation. We also examine a toy model of a non-BCS superconductor (e.g. high $T_c$ superconductors) in terms of an EMAM. The models presented give a common, simple picture of these two systems in terms of an EMAM. The presence of an EMAM in these systems might be tested through the observation of the decay modes of a charged, spin zero unstable particle inside one of these systems.Comment: 17 pages, no figures, to be published in Phys. Rev.