Disorder, dipolar, and quadrupolar physics of the square lattice oxyhalides DyOX (X=Cl,Br,I)*

"Rare-earth ions are an important ingredient in frustrated magnetism due to their propensity for anisotropic magnetization distributions. Due to this and their crystal field splitting allowing for an effective spin-½ degrees of freedom, they are commonly investigated in the search for exotic magnetic phases of matter. The Dysprosium Oxy-halides (DyOX, X=Cl,Br,I) have come under recent investigation as layered Van der Waals materials [1], with interplanar spacing being a function of the halide's ionic radius. This, paired with Dysprosium's large magnetic moment and single-ion quadrupolar behavior, leads DyOX to be an exciting platform to study specific aspects of quantum magnetism that are generally difficult to probe. This talk will present several forms of data: neutron diffraction and scattering, thermomagnetic measurements, and simulation results to elucidate their magnetic properties. The results systematically show two ordering transitions, yet dramatically different magnetic structures across the family of compounds. Of particular interest is a disordered magnetic structure that arises with increased interplanar spacing. We will compare these compounds' magnetic properties, as well as the origin of these novel behaviors."

[1] Tian, Congkuan, Feihao Pan, Le Wang, Dehua Ye, Jieming Sheng, Jinchen Wang, Juanjuan Liu, et al. "DyOCl: A Rare-Earth Based Two-Dimensional van Der Waals Material with Strong Magnetic Anisotropy." Physical Review B 104, no. 21 (December 7, 2021): 214410. https://doi.org/10.1103/PhysRevB.104.214410.