69 citations · 397 across the 22 of their papers we have counts for
6 papers · 1 filter
Phase transitions in diluted negative-weight percolation models
L. Apolo, O. Melchert, A. K. Hartmann
We investigate the geometric properties of loops on two-dimensional lattice graphs, where edge weights are drawn from a distribution that allows for positive and negative weights.…
Extended scaling for ferromagnetic Ising models with zero-temperature transitions
Helmut G. Katzgraber, I. A. Campbell, A. K. Hartmann
We study the second-moment correlation length and the reduced susceptibility of two ferromagnetic Ising models with zero-temperature ordering. By introducing a scaling variable mot…
Ultrametricity and clustering of states in spin glasses: A one-dimensional view
Helmut G. Katzgraber, Alexander K. Hartmann
We present results from Monte Carlo simulations to test for ultrametricity and clustering properties in spin-glass models. By using a one-dimensional Ising spin glass with random p…
New Insights from One-Dimensional Spin Glasses
Helmut G. Katzgraber, Alexander K. Hartmann, A. P. Young
The concept of replica symmetry breaking found in the solution of the mean-field Sherrington-Kirkpatrick spin-glass model has been applied to a variety of problems in science rangi…
Replica theory for Levy spin glasses
K. Janzen, A. K. Hartmann, A. Engel
Infinite-range spin-glass models with Levy-distributed interactions show a spin-glass transition with similarities to both the Sherrington-Kirkpatrick model and to disordered spin…
X-Ray Propagation in Tapered Waveguides: Simulation and Optimization
Sebastian Panknin, Alexander K. Hartmann, Tim Salditt
We use the parabolic wave equation to study the propagation of x-rays in tapered waveguides by numercial simulation and optimization. The goal of the study is to elucidate how beam…