Materialization of a Geometrically Frustrated Magnet in a Hybrid Coordination Framework: A Study of the Iron(II) Oxalate Fluoride Framework, KFe(C2O4)F

Here we discuss magnetic hybrid coordination frameworks in relation to the realization of new geometrically frustrated magnets. In particular, we present the nuclear and magnetic structures of one such system—the Fe2+-based oxalate fluoride framework KFe(C2O4)F—through analysis of the powder neutron diffraction and muon spectroscopy data. KFe(C2O4)F retains an orthorhombic Cmc21 structure upon cooling to 2 K composed of quasi-one-dimensional iron fluoride chains connected to a distorted triangular network via oxalate anions. Previous magnetometry measurements of KFe(C2O4)F indicate that it is a strongly interacting system with a Weiss constant θ ≈ −300 K that undergoes a magnetic ordering transition at TN ≈ 20 K, yielding a frustration index, f = |θ|/TN ≈ 15, reflective of high-spin frustration. We determine the nature of this frustrated antiferromagnetic ordering below TN and show that the resulting magnetic structure is best described by a model in the Cmc′21′ magnetic space group

Two-dimensional spin liquid behaviour in the triangular-honeycomb antiferromagnet TbInO₃

Spin liquid ground states are predicted to arise within several distinct scenarios in condensed matter physics. The observation of these disordered magnetic states is particularly pervasive among a class of materials known as frustrated magnets, in which the competition between various magnetic exchange interactions prevents the system from adopting long-range magnetic order at low temperatures. Spin liquids continue to be of great interest due to their exotic nature and the possibility that they may support fractionalized excitations, such as Majorana fermions. Systems that allow for such phenomena are not only fascinating from a fundamental perspective but may also be practically significant in future technologies based on quantum computation. Here we show that the underlying antiferromagnetic sublattice in TbInO3 can undergo a crystal field-induced distortion of its buckled triangular arrangement to one based on a honeycomb. The absence of a conventional magnetic ordering transition at the lowest measurable temperatures indicates that another critical mechanism must govern in the ground-state selection of TbInO3. We suggest that anisotropic exchange interactions—mediated through strong spin–orbit coupling on the emergent honeycomb lattice of TbInO3—give rise to a highly frustrated spin liquid