Observation of ferromagnetic surface of paramagnetic YCo2
Dedkov, Yury1; Laubschat, Clemens1; Khmelevskyi, Serguei2; Redinger, Josef2; Mohn, Peter2; Weinert, Michael3
1Germany;
2Austria;
3United States

Recent theoretical work has suggested that magnetism in reduced dimensions (films, surfaces, or small clusters) is not a priori restricted to those elements exhibiting magnetism in the bulk. Therefore, the observation and the understanding of the nature of magnetism in low-dimensional systems, especially of surface magnetism, has been the subject of many efforts in the last two decades. The importance of this phenomenon can hardly be overestimated, as it yields not only impressive experimental results on its own, but opens the field for major breakthroughs in impetuously developed science (physics, chemistry, biology) and technology, for instance in nanotechnology.
In the present contribution we demonstrate undisputable results on the experimental observation of intrinsic surface magnetism of the bulk paramagnetic material YCo2. As predicted by theory, the observed magnetism of the low-index crystallographic (111) plane of YCo2 is explained by the increased of density of electronic states at the Fermi level due to the reduced atomic coordination at the surface. Since this magnetic order exists at room temperature, YCo2 shows great potential for an application in magnetic nanotechnology.
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