Galileo's Sky

是一種鐵電(ferromagnectic)物質導電性會隨著磁場改變而產生變化的現象,
隨著磁場大小的變化, 電阻便隨之改變, 利用這種現象,
可以拿來作磁場感測計, 也有用來做非揮發性記憶體 (NVRAM), 例如 MRAM, 硬碟片讀寫頭等.

這裡又提到了一個相關的物理現象 giant magnetoresistance (GMR, 巨磁阻),
是一種量子現象, 跟電子自旋(spin)有關, 所以這和 Hall effect (霍爾效應) 看起來是不同的機制,
看起來很有趣, 有空再繼續挖下去囉!

這週末要是上不了大雪山森林遊樂區, 就來好好研究一下





節錄自 Wikipedia:

Magnetoresistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied to it. The effect was first discovered by William Thomson in 1856, but he was unable to lower the electrical resistance of anything by more than 5%. This effect was later called ordinary magnetoresistance (OMR). More recent researchers discovered materials showing giant magnetoresistance (GMR), colossal magnetoresistance (CMR) and magnetic tunnel effect (TMR).