Crystal Electric Field (CEF) Effect in CeIr3Ge7 and YbIr3Ge7

We recently discovered new members of the stoichiometric 1-3-7 family of crystals including YbRh3Si7, YbIr3Ge7, CeIr3Ge7, and YbIr3Si7, whose magnetic and transport properties reflect large crystal electric field(CEF) anisotropy. Inelastic neutron scattering measurements on CeIr3Ge7 and YbIr3Ge7 will allow us to directly measure their CEF transitions from which we can then parameterize their single ion Hamiltonians. This analysis will definitively establish the nature of their spin anisotropies and the g-tensor of their ground state doublet, from which we can determine the size of the magnetic moment reduced by crystal field effects. Our studies thus far have revealed the importance of single ion properties in these two materials and it is thus crucial that we directly measure their CEF schemes to understand the origins of these effects.