Magnetic structure of a Pd-doped Honeycomb Kondo Lattice Ce(Pt1-xPdx)6Al3

Recently the Honeycomb lattice has attracted considerable attraction due to the bond dependent exchange interactions according to the Kitaev model, resulting in a quantum spin-liquid ground state previously identified in -RuCl3. We have synthesised a new Ce-based Honeycomb lattice compound CePt6Al3, which exhibits heavy-fermion behaviour and no clear sign of long-range magnetic ordering down to 0.05 K. At low temperatures the resistivity exhibits T2 behaviour without showing any anomaly down to 0.05 K. The heat capacity (C/T) exhibits a broad maximum of 0.5 J/K2 mol at around 0.55 K. The ground state appears to be a heavy-fermion state where the Kondo effect and frustration cooperatively prevent the Ce magnetic moments in the honeycomb lattice from long-range ordering. Interestingly, the heat capacity of Ce(Pt1-xPdx)6Al3 with x = 0.1-0.3 exhibits a λ-type peak between 2 and 3 K indicating a long-range magnetic ordering, which is confirmed by our muon spin rotation measurements. We therefore propose to investigate the magnetic structure of Ce(Pt1-xPdx)6Al3 with x=0.1 and 0.3 using the high flux WISH diffractometer.