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We will make a link between the steepest descent method for an unconstrained minimisation problem and fixed-point iterations for its Euler-Lagrange equation. In this context, we shall rediscover the preconditioned nonlinear conjugate…

Numerical Analysis · Mathematics 2023-04-12 Pascal Heid

Finite difference based micromagnetic simulations are a powerful tool for the computational investigation of magnetic structures. In this paper, we demonstrate how the discretization of continuous micromagnetic equations introduces a…

Materials Science · Physics 2024-12-17 Samuel J. R. Holt , Andrea Petrocchi , Martin Lang , Swapneel A. Pathak , Hans Fangohr

The magnetic phase diagram of a plaquette dimerized antiferromagnetic system is studied by using a combination of numerical and analytical techniques. For the strongly frustrated regime, series expansions and bond operators techniques are…

Strongly Correlated Electrons · Physics 2017-07-05 F. Elias , M. Arlego , C. A. Lamas

The magnetocaloric effect (MCE) in the A-site ordered manganite NdBaMn2O6 is studied. The MCE in this compound has an anomalous behavior. In low magnetic fields, the abrupt transitions between direct and inverse magnetocaloric effect are…

Materials Science · Physics 2012-02-20 A. M. Aliev , A. G. Gamzatov , V. S. Kalitka , A. R. Kaul

The degradation mechanisms of AlGaN/GaN HEMTs adopting Fe and C co-doping, with high and low carbon doping concentration were investigated by means of hot-electron step stress and 24 hours stress tests. Firstly, DC and EL characterization…

Applied Physics · Physics 2021-08-02 Z. Gao , F. Rampazzo , M. Meneghini , C. De Santi , F. Chiocchetta , D. Marcon , G. Meneghesso , E. Zanoni

We investigate weakly coupled spin-1/2 ladders in a magnetic field. The work is motivated by recent experiments on the compound (C5H12N)2CuBr4 (BPCB). We use a combination of numerical and analytical methods, in particular the density…

We present and analyze a preconditioned conjugate gradient method (PCG) for solving spatial network problems. Primarily, we consider diffusion and structural mechanics simulations for fiber based materials, but the methodology can be…

Numerical Analysis · Mathematics 2022-07-18 Morgan Görtz , Fredrik Hellman , Axel Målqvist

We study the magnetic properties of electron in a constant magnetic field and confined by a isotropic two dimensional harmonic oscillator on a space where the coordinates and momenta operators obey generalized commutation relations leading…

Quantum Physics · Physics 2009-11-13 Khireddine Nouicer

We simulate a finite system of $N$ confined electrons with inclusion of the Darwin magnetic interaction in two- and three-dimensions. The lowest energy states are located using the steepest descent quenching adapted for velocity dependent…

Statistical Mechanics · Physics 2009-10-31 Vishal Mehra , Jayme De Luca

We consider the coupled system of the Landau--Lifshitz--Gilbert equation and the conservation of linear momentum law to describe magnetic processes in ferromagnetic materials including magnetoelastic effects in the small-strain regime. For…

Numerical Analysis · Mathematics 2025-01-15 Hywel Normington , Michele Ruggeri

Magnetic fields spontaneously grow at unstable interfaces around hot-spot asymmetries during inertial confinement fusion implosions. Although difficult to measure, theoretical considerations and numerical simulations predict field strengths…

Plasma Physics · Physics 2022-07-20 James D. Sadler , Christopher A. Walsh , Ye Zhou , Hui Li

We demonstrate a straightforward approach to integrating a magnetic field into a low-temperature scanning tunneling microscope (STM) by adhering an NdFeB permanent magnet to a magnetizable sample plate. To render our magnet concept…

The density matrix renormalization group (DMRG) method and its applications to finite temperatures and two-dimensional systems are reviewed. The basic idea of the original DMRG method, which allows precise study of the ground state…

Strongly Correlated Electrons · Physics 2009-11-10 Naokazu Shibata

We study gradient compression methods to alleviate the communication bottleneck in data-parallel distributed optimization. Despite the significant attention received, current compression schemes either do not scale well or fail to achieve…

Machine Learning · Computer Science 2020-02-19 Thijs Vogels , Sai Praneeth Karimireddy , Martin Jaggi

We investigate weakly coupled spin-1/2 ladders in a magnetic field. The work is motivated by recent experiments on the compound $\mathrm{(C_5H_{12}N)_2CuBr_4}$ (BPCB). We use a combination of numerical and analytical methods, in particular…

Strongly Correlated Electrons · Physics 2012-01-26 Pierre Bouillot

We study gradient magnetometry with an ensemble of atoms with arbitrary spin. We calculate precision bounds for estimating the gradient of the magnetic field based on the quantum Fisher information. For quantum states that are invariant…

Quantum Physics · Physics 2018-06-08 Iagoba Apellaniz , Inigo Urizar-Lanz , Zoltan Zimboras , Philipp Hyllus , Geza Toth

Efficient algorithms for the calculation of minimum energy paths of magnetic transitions are implemented within the geodesic nudged elastic band (GNEB) approach. While an objective function is not available for GNEB and a traditional line…

Computational Physics · Physics 2020-11-30 Aleksei V. Ivanov , Damjan Dagbartsson , Julien Tranchida , Valery M. Uzdin , Hannes Jónsson

This survey explores the development of adjoint Monte Carlo methods for solving optimization problems governed by kinetic equations, a common challenge in areas such as plasma control and device design. These optimization problems are…

Numerical Analysis · Mathematics 2024-05-24 Russel Caflisch , Yunan Yang

We introduce a hybrid approach to applying the density matrix renormalization group (DMRG) to continuous systems, combining a grid approximation along one direction with a finite Gaussian basis set along the remaining two directions. This…

Chemical Physics · Physics 2017-08-02 E. Miles Stoudenmire , Steven R. White

We study the effect of an applied magnetic field on sub-10nm wide MoGe and Nb superconducting wires. We find that magnetic fields can enhance the critical supercurrent at low temperatures, and does so more strongly for narrower wires. We…

Superconductivity · Physics 2009-11-11 A. Rogachev , T. -C. Wei , D. Pekker , A. T. Bollinger , P. M. Goldbart , A. Bezryadin