Contributions of muon spin rotation/relaxation/resonance to the understanding of problems in magnetism — Current and future

During these 25 years following the start of muon spin rotation/relaxation/resonance (µSR) studies on condensed matter, various new aspects of magnetic materials have been explored by using high sensitivity to the microscopic dynamical behaviour of the host magnetism, specifically, the studies on magnetic ordering in strongly-correlated electron systems, elementary excitations in conducting polymers and protein, etc. Intense (more than 106/cm·s) and ultra-slow (below keV) muon beams to be available at future accelerator facilities may open new areas such as spin dynamics studies of surface magnetism, cluster particles, etc.