For example, present-day read heads in computer hard drives use a device dubbed a spin valve, wherein a layer of a nonmagnetic metal is sandwiched between two ferromagnetic metallic layers.

• 例如，目前的硬碟读写头使用了类似自旋阀的元件，其构造是一层非磁性金属夹在二层铁磁金属中间。