The magnet creates a field which changes the polarity of a tiny, tiny portion of the metal particles which coat each platter's surface.

这个磁体创建一个,能改变覆盖在,磁盘表面小金属粒子的磁极。

哈佛公开课 - 计算机科学课程节选

Basically what he did is he took a very thin metal foil and he bombarded it with charged particles.

简单的说他做的工作是,用一张非常薄的金属箔,然后用带电的粒子轰击它。

麻省理工公开课 - 固态化学导论课程节选