论文标题
在旋转场中的磁珠的反旋转
Counter-rotation of magnetic beads in spinning fields
论文作者
论文摘要
磁场中的磁化珠试图通过将其磁性力矩与磁场方向排列并朝着磁场强度的最大移动来最大程度地减少其磁自由能。但是，当珠子耦合到基材时，它被迫滚动。两个原本独立的自由度，翻译和旋转程度变得紧密耦合，从而产生微妙的，通常是违反直觉的效果。在这里，我们研究了这样一个，很容易再现的，但令人惊叹的效果：放置在实验室磁力搅拌器顶部的neodymium珠。当搅拌器的磁铁以缓慢的速度旋转时，珠自然会跟随该场。然而，令人惊讶的是，在高旋转速率下，珠突然颠倒了它的方向，并使观察者的方向惊讶，朝相反的方向违背了驾驶场的方向。在[j.magn.magn.matter，476，476，476，376-381，（2019），（2019年）中，实验进行了实验，并在此处进行了数字拟合，并进行了数字拟定。
A magnetized bead in a magnetic field seeks to minimize its magnetic free energy by aligning its magnetic moment with the field direction and by moving towards the maximum of the field's intensity. However, when the bead is coupled to a substrate it is forced to roll. The two otherwise independent degrees of freedom, translation and rotation, become tightly coupled giving rise to subtle and often counterintuitive effects. Here we investigate one such, easily reproducible, yet stunning effect : A neodymium bead placed on top of a laboratory magnetic stirrer. When the stirrer's magnet spins at slow rates the bead naturally follows the field. However, surprisingly, at high spinning rates the bead suddenly inverts its direction and runs, to the surprise of the observer, in the opposite direction, against the driving field direction.This effect, experimentally investigated in [J.Magn.Magn.Matter, 476, 376-381, (2019)], is here comprehensively studied, with numerical simulations and a theoretical approach complementing experimental observations.
