Samarium (Sm, element 62) is a singular element to study with neutron scattering. It has a very large neutron absorption, a magnetic form factor that peaks at high Q, and often a low magneto-crystalline anisotropy due to the limited basis of single-ion states. We use polarization techniques to study the ground state of Kitaev candidate SmI$_3$, a 2D honeycomb material that is similar to other...
Rare earth trihalides are gaining attention in the field of quantum matter for their potential to exhibit exotic ground states due to interacting magnetic moments with competing interactions or geometrical frustration. Compounds such as YbBr3 and ErBr3 exemplify this interest with their unique 2D honeycomb structures where magnetic anisotropy can be tuned by varying the rare-earth ion,...
Normal spinels AM$_2$O$_4$ crystallize in the cubic space group Fd-3m at room temperature. The magnetic ions M form a pyrochlore sublattice, consisting of a network of corner-sharing tetrahedra prone to magnetic frustration. Complex magnetic ground states arise in these spinel compounds from a strong competition between magnetic interactions beyond the third neighbor [1-5]. In this talk, we...
Tb2Ti2O7 has remained an enigma in condensed matter physics, and more specifically in the field of frustrated magnetism, for about two decades [1]. This material evades long-range order down to temperature as low as 20 mK and its ground state exhibits puzzling diffuse magnetic scattering [2,3]. Its low energy spin dynamics includes, on the one hand, an exciton located at about = 1.5 meV,...
The octahedrally and tetrahedrally coordinated Fe3+ (S=5/2) ions in Bi2Fe4O9 form a quasi two-dimensional Cairo pentagonal lattice (Pbam). Combined with predominantly antiferromagnetic interactions, this leads to a strong frustration with Tn=245 K while $θ_{CW}=-1670$ K in a fairly unexplored geometry. The magnetic structure for T<Tn can be indexed with k=(½, ½, ½) with a noncollinear magnetic...
The interplay between the quantum effects from low-dimensionality and the spin-orbit coupling leads to exotic ground states with unusual excitations. Among the diverse 2D spin systems, the S = ½ 2D square lattice has piqued the curiosity of researchers due to its connection with the High-Temperature Superconductivity (HTSC). Studying the Crystal electric field (CEF) and spin-orbit coupling...
