Antiferromagnetic order in the honeycomb Kondo lattice CePt6Al3 induced by Pd substitution

The cerium-based compound CePt6Al3, in which Ce atoms form a honeycomb lattice hosting magnetic frustration, has a heavy-fermion ground state. We have observed development of magnetic order in partially Pd-substituted Ce(Pt1-xPdx)(6)Al-3 series up to x = 0.3 by the measurements of magnetic susceptibility, electrical resistivity rho, and specific heat C. In the whole range of x, the unit cell volume remains unchanged within 0.2%, and the effective magnetic moment stays at 2.4 mu(B)/Ce. For x = 0.05, both C/T and rho(T) jump on cooling at T-m = 1.8 K. With increasing x to 0.2, T-m increases to 3.8 K, where C/T shows a pronounced A-type anomaly. Application of magnetic fields suppresses T-m, which is indicative of an antiferromagnetic (AFM) ordered state. Thus, a long-range AFM order is induced by the substitution of isovalent Pd for Pt in CePt6Al3 without carrier doping and chemical pressure. We attribute the emergence of AFM order in Ce(Pt1-xPdx)(6)Al-3 to the randomness in the spin-orbit interaction in the Pt-Pd sublattice, which weakens both the coherent Kondo effect and magnetic frustration in the honeycomb Kondo lattice.

Automated summary

In the CePt6Al3 compound, the development of magnetic order is observed with partial Pd substitution, and as the amount of Pd substitution increases, the antiferromagnetic ordered state becomes stronger.