Spin gaps in the ordered states of La2LiXO6(X=Ru,Os) and their relation to the distortion of the cubic double perovskite structure in 4d3 and 5d3 magnets

Time-of-flight inelastic neutron scattering measurements have been carried out on polycrystalline samples of the 4d3 and 5d3 double pervoskite antiferromagnets La2LiRuO6 and La2LiOsO6. These reveal the development of an inelastic spin gap in La2LiRuO6 and La2LiOsO6 of ∼1.8(8) and 6(1) meV, below their respective ordering temperatures TN,∼23.8 and 30 K. The bandwidths of the spin excitations are shown to be ∼5.7(9)and12(1)meV, respectively, at …