Microscopic Evidence for Long-Range Magnetic Ordering in the Γ8Ground Quartet Systems SmTr2Al20(Tr: Ti, V, Cr)

We report on muon spin relaxation (µSR) studies of Sm Tr 2 Al 20 ( Tr : Ti, V, Cr) with a cubic Γ 8 crystalline-electric-field ground state. A coherent muon spin precession was observed below the phase transition temperature in a zero applied field for each compound, manifesting long-range magnetic ordering from a microscopic point of view. The muon spin precession frequency distribution is qualitatively different among the three compounds, indicating differences in the magnetic structure and/or the muon stopping site.