Speaker
Description
Materials realizing the scaling behavior of the XY model in two dimensions (2D) are sparse. Here we report on comprehensive neutron triple-axis measurements conducted at the FRM2, BER2, and ILL to investigate the critical static and dynamical magnetic fluctuations in the layered ruthenates Ca$_{2}$RuO$_{4}$ (CRO214) and Ca$_{3}$Ru$_2$O$_{7}$ (CRO327). Specifically, we probe the temperature-dependence of the antiferromagnetic (AFM) Bragg-intensity, the $Q$-width, the amplitude, and the energy-width of the magnetic diffuse scattering in vicinity to the Neel temperature $T_N$ to determine the critical behaviour of the magnetic order parameter $M$, correlation length $\xi$, susceptibility $\chi$, and the characteristic energy $\Gamma$. We find that - in spite of distinct magnetic structures - the critical behaviours of CRO214 and CRO327 follow similar universal scaling laws that are compatible with predictions of the 2D-XY model. Hence, our results suggest that single- and bilayer ruthenates provide new platforms to study the 2D-XY model in solid-state materials.
