Electronic and magnetic ground state of 4d3double perovskite ruthenates A2LaRuO6(A = Ca, Sr, Ba).

4dtransition metal oxide offers an intriguing puzzle for its electronic and magnetic ground state. They are in the crossover regime of strong spin-orbit interaction (SOI) and electron-electron correlation (U) with quenched orbital angular momentum. Our work unravels the electronic and magnetic ground state of the less investigated 4d3double perovskite ruthenates A2LaRuO6(A = Ca, Ba). The negligible effect of SOI is evident from the bulk magnetic, specific heat measurements, and density functional theory (DFT) calculations, indicating a classical spin-only magnetic ground state (S= 3/2) for the materials. Magnetization measurements show that both materials have long-range antiferromagnetic order with a high degree of magnetic frustration (f≈13-15). Interestingly, a nearT2- behavior is observed in low-Tmagnetic heat capacity measurement, indicating the presence of low-dimensional spin wave excitation and magnetic frustration in both materials. The temperature-dependent resistivity measurements and electronic band structure calculations confirm a conventional Mott insulating ground state in these two systems. Moreover, our experimental investigation and DFT calculations highlight the reason for the nonexistence of Sr2LaRuO6.