The Exploration of Thulium Halides and Oxyhalides as Strongly Fluctuating Quantum Magnets

Quantum spin liquids (QSL) are an exotic state of matter in which the ground state is composed of highly entangled spins. This research explores the possibility of finding QSLs composed of the rare earth metal Thulium in a Halide structure. Three Rare Earth Halides TmX₃ (X = Cl, Br, I) are studied to determine their magnetic properties and crystalline structure. The Oxy-Halide TmOCl was also synthesized to control for the material structure’s effect on the properties of Thulium. Measurements of the magnetic susceptibility down to 1.8K of each Halide reveal the possible beginning of a magnetic phase transition for all three compounds and especially so for TmBr₃ and TmI₃. A linear fit was performed on the inverse susceptibility data for each compound to determine the Curie-Weiss Temperature which revealed that all four compounds were antiferromagnetic. Based on these results and an analysis of each compound’s molecular structure, additional heat capacity measurements were taken on TmI₃, which revealed possible anisotropic behavior below 1.5K. Additional heat capacity and X-ray diffraction measurements will need to be performed in order to determine the magnetic properties and molecular structure of every compound.