Singha, AparajitaDonati, FabioWackerlin, ChristianBaltic, RomanaDreiser, JanPivetta, MarinaRusponi, StefanoBrune, Harald2016-07-192016-07-192016-07-19201610.1021/acs.nanolett.5b05214https://infoscience.epfl.ch/handle/20.500.14299/127640WOS:000377642700009We report magnetic hysteresis in Er clusters on. Cu(111) starting from the size-of three atoms. combining Xray magnetic circular dichroism, scanning tunneling microscopy, and mean-field nucleation theory, we determine the size dependent magnetic properties of the Er clusters. Er atoms and dimers-are paramagnetic, and their easy magnetization axes are oriented in-plane. In contrast, timers and bigger dusters exhibit magnetic hysteresis at 2.5 K with a relaxation time of 2 min at 0.1 T and out-of-plane easy axis. This appearance of magnetic stability for trimers coincides with their enhanced structural stability.Rare earth clustersX-ray magnetic circular dichroismscanning tunneling microscopysuperlatticehysteresismagnetic anisotropytext::journal::journal article::research article