MACROSCOPIC QUANTUM TUNNELING OF THE MAGNETIC-MOMENT (INVITED)

The magnetization vector in solids is traditionally viewed as a classi cal variable. Recent theoretical and experimental works have demonstra ted, however, that it can tunnel quantum mechanically between metastab le magnetic states. Examples are tunneling of the magnetic moment betw een equilibrium orientations in monodomain ferromagnetic particles, tu nneling of the Neel vector in antiferromagnetic particles, and tunneli ng of domain walls through the pinning barriers in bulk materials. The ory, experiments, and open questions will be reviewed.