A magnetic tunnel junction (MTJ) is a device made up of two ferromagnetic layers separated by a thin insulating layer. When a voltage is applied, electrons can tunnel through the insulator, allowing the device to switch between different magnetic states. This property makes MTJs useful in various applications, including data storage and memory devices. MTJs are essential components in technologies like spintronics, which exploit the spin of electrons in addition to their charge. They are also used in MRAM (Magnetoresistive Random Access Memory), offering faster speeds and lower power consumption compared to traditional memory technologies.