The magnetic crossover diagram of RbCuF3

KCuF3 is a famous quasi-one-dimensional S = ½ Heisenberg antiferromagnet, which displays many novel quantum magnetic properties including high-temperature dynamics, quantum critical scaling and signals of entanglement. In contrast, the other ACuF3 (A = Ag, Rb,NH4/ND4) have not been as deeply investigated due to the difficulties of procuring high quality single crystals. We have grown the first single crystal of RbCuF3 that is of a high enough quality for neutron spectroscopy. We propose to use MERLIN to investigate whether the dimensional crossover found in KCuF3 exists in RbCuF3 via the magnetic excitation spectrum. If the longitudinal mode is present in RbCuF3, we can identify not only whether RbCuF3 behaves like a 1D Luttinger liquid, but also the energy and temperature ranges over which the quantum critical point dominates.