Stoop Ralph L, Straube Arthur V, Johansen Tom H, Tierno Pietro
Departament de Física de la Matèria Condensada, Universitat de Barcelona, 08028 Barcelona, Spain.
Department of Mathematics and Computer Science, Freie Universität Berlin, 14195 Berlin, Germany.
Phys Rev Lett. 2020 Feb 7;124(5):058002. doi: 10.1103/PhysRevLett.124.058002.
We investigate the directional locking effects that arise when a monolayer of paramagnetic colloidal particles is driven across a triangular lattice of magnetic bubbles. We use an external rotating magnetic field to generate a two-dimensional traveling wave ratchet forcing the transport of particles along a direction that intersects two crystallographic axes of the lattice. We find that, while single particles show no preferred direction, collective effects induce transversal current and directional locking at high density via a spontaneous symmetry breaking. The colloidal current may be polarized via an additional bias field that makes one transport direction energetically preferred.
我们研究了顺磁性胶体粒子单层在磁性气泡三角晶格上驱动时产生的定向锁定效应。我们使用外部旋转磁场来产生二维行波棘轮，迫使粒子沿着与晶格的两个晶轴相交的方向传输。我们发现，虽然单个粒子没有显示出偏好方向，但集体效应通过自发对称性破缺在高密度下诱导横向电流和定向锁定。胶体电流可以通过一个额外的偏置场极化，该偏置场使一个传输方向在能量上更受青睐。
