Tsis tshua muaj lub ntiaj teb cov hlau nplaum ruaj khov, tshwj xeeb tshaj yog cov khoom siv xws li neodymium, samarium-cobalt, thiab lwm yam, ua lub luag haujlwm tseem ceeb hauv ntau lub tshuab kho mob thiab cov cuab yeej siv hauv tsev kho mob. Lawv cov khoom tshwj xeeb, xws li lub zog sib nqus siab thiab ua haujlwm rau demagnetization, ua rau lawv zoo tagnrho rau ntau daim ntawv thov tseem ceeb.