arXiv subjects
Publications and source records attributed to A. M. Tikofsky.
We compute the dynamical magnetic susceptibility of the t-J model in its commensurate flux phase at low hole doping. We compare the calculations with experiments and exact diagonalization studies.
We describe paired quantum Hall states at filling fractions $ν$, where $ν^{-1}$ is an integer, and present explicit wavefunctions for these states. Experiments are proposed to distinguish between paired states of singlet and triplet symmetry. It is argued from existing experimental data that the $ν=1/2$ state observed in double layer quantum wells is a singlet and not a triplet paired state. In contrast, this state has been interpreted as a `3-3-1 state' which is a triplet paired state.
The energetic properties of a paired quantum Hall state at Landau level filling $ν=2$ are investigated using variational Monte Carlo techniques. Pairing is found to be energetically favorable in small magnetic fields because it introduces correlations between up and down spins that are absent in the traditional $ν=2$ state. We find that pairing survives extrapolation to the thermodynamic limit.
We argue that a new type of quantum Hall state requiring non-perturbative Landau level mixing arises at low electron density. In these states, up and down spin electrons pair to form spinless bosons that condense into a bosonic quantum Hall state. We describe a wavefunction for a paired quantum Hall state at $ν=2$ and argue that it is stabilized by a BCS instability arising in flux attachment calculations. Based on this state, we derive a new global phase diagram for the integral quantum Hall effect with spin. Additional experimental implications are discussed.
We consider a layered superconductor with a complex order parameter whose phase switches sign from one layer to the next. This system is shown to exhibit gapless superconductivity for sufficiently large interlayer pairing or interlayer hopping. In addition, this description is consistent with experiments finding signals of time-reversal symmetry breaking in high-temperature superconductors only at the surface and not in the sample bulk.