New Bending Algorithm for Field-Driven Molecular Dynamics

Abstract

A field-driven bending method is introduced in this paper according to the coordinate transformation between straight and curved coordinates. This novel method can incorporate with the periodic boundary conditions in analysis along axial, bending, and transverse directions. For the case of small bending, the bending strain can be compatible with the beam theory. Consequently, it can be regarded as a generalized SLLOD algorithm. In this work, the bulk copper beam under bending is analyzed first by the novel bending method. The bending stress estimated here is well consistent to the results predicted by the beam theory. Moreover, a hollow nanowire is also analyzed. The zigzag traces of atomic stress and the corresponding 422 common neighbor type can be observed near the inner surface of the hollow nanowire, which values are increased with an increase of time. It can be seen that the novel bending method with periodic boundary condition along axial direction can provide a more physical significance than the traditional method with fixed boundary condition.

An Investigation on the Characteristics of Bending, Buckling and Vibration of Nanobeams via Nonlocal Beam Theory

“…Nowadays, it is still a challenge to study the mechanics of nanomaterials by means of experimental tests due to the difficulties encountered on the nanoscale. Therefore, the theoretical methods such as atomistic simulations and continuum mechanics theories are often used to analyze the bending, buckling and dynamic responses of nanostructures [Reddy (2007); Chen et al (2010); ; Roque et al (2011)].…”

Single‐Shot Laser‐Induced Switching of an Exchange Biased Antiferromagnet

“…[17][18][19] Detailed time-resolved studies of dynamics showed that the characteristic timescale of laserinduced exchange bias quenching in a polycrystalline Co/IrMn bilayer is 0.7 ± 0.5 ps, attributing the rapid decrease in exchange coupling to a spin disorder at the interface created by laser heating. [17] In our case, the demagnetization and switching dynamics after a 40 fs laser pulse illumination of the annealed IrMn(5)/Co 77 Gd 23 (4) sample have been studied as a function of time for various laser fluences (Figure 3a) and for different applied fields intensities (Figure 3b). A Co demagnetization time of ≈700 fs could be measured, which is independent of the applied field.…”

“…First, single-pulse laser switching experiments have been performed by exciting an IrMn(5)/Co 77 Gd 23 (4) sample from the top CoGd surface (Figure 1a). Using a single laser pulse of 40 fs with a fluence of 17 mJ cm -2 , induces a reversal of the exchange field from 154 to −26 mT, as reported in Figure 2a.…”

“…Initializing exchange bias is a complex process and is done by heating the system above the Néel temperature T N or at least the blocking temperature T B of the AFM layer and cooling down with the FM layer in a saturated state, with or without an applied magnetic field. [3,4] This thermal annealing can be done in a quasi-static way (annealing for several hours), using rapid annealing or continuous laser sweeping on the surface. [5,6] Recent studies have demonstrated that spin currents can be used to manipulate exchange bias thanks to spin-orbit torque without any applied magnetic field.…”