Spin-momentum locking is a phenomenon observed in certain materials, particularly in topological insulators and graphene. In these materials, the spin of electrons is directly linked to their momentum, meaning that the direction of an electron's spin is determined by its movement. This unique relationship can lead to new electronic properties and behaviors. This effect can be harnessed in various applications, such as in spintronics, where both the charge and spin of electrons are utilized for information processing. By manipulating spin-momentum locking, researchers aim to develop faster and more efficient electronic devices, potentially revolutionizing technology.