34 research outputs found
Extracting the intrinsic switching field distribution in perpendicular media: a comparative analysis
We introduce a new method based on the first-order-reversal-curve (FORC)
diagram to extract the intrinsic (microscopic) switching-field distribution
(SFD) of perpendicular recording media (PRM). To demonstrate the viability of
the method, we micromagnetically simulated FORCs for PRM with known SFD and
compare the extracted SFD with the SFD obtained by means of two different
methods that are based on recoil loops, too, which however rely on mean-field
approximations and assumptions on the shape of the SFD. The FORC method turns
out to be the most accurate algorithm over a broad range of dipolar interaction
strengths, where the other methods overestimate the width of the SFD.Comment: 3 pages with 2 figures, 3 supplemental figures; submitted to J. Appl.
Phys. (MMM Annual Conference Proceedings
Superconducting single-charge transistor in a tunable dissipative environment
We study a superconducting single-charge transistor, where the coherence of
Cooper pair tunneling is destroyed by the coupling to a tunable dissipative
environment. Sequential tunneling and cotunneling processes are analyzed to
construct the shape of the conductance peaks and their dependence on the
dissipation and temperature. Unexpected features are found due to a cross-over
between two distinct regimes, one `environment-assisted' the other
`environment-dominated'. Several of the predictions have been confirmed by
recent experiments. The model and results apply also to the dynamics of
Josephson junction quantum bits on a conducting ground plane, thus explaining
the influence of dissipation on the coherence.Comment: Strongly revied version as accepted by Phys. Rev. Let
Density of States and Critical Behavior of the Coulomb Glass
We present zero-temperature simulations for the single-particle density of
states of the Coulomb glass. Our results in three dimensions are consistent
with the Efros and Shklovskii prediction for the density of states.
Finite-temperature Monte Carlo simulations show no sign of a thermodynamic
glass transition down to low temperatures, in disagreement with mean-field
theory. Furthermore, the random-displacement formulation of the model undergoes
a transition into a distorted Wigner crystal for a surprisingly broad range of
the disorder strength.Comment: 4 pages, 2 figures, 1 tabl