showing 4 related works from this author
Spin-chain correlations in the frustrated triangular lattice material CuMnO$_2$
2020
The Ising triangular lattice remains the classic test-case for frustrated magnetism. Here we report neutron scattering measurements of short range magnetic order in CuMnO$_2$, which consists of a distorted lattice of Mn$^{3+}$ spins with single-ion anisotropy. Physical property measurements on CuMnO$_2$ are consistent with 1D correlations caused by anisotropic orbital occupation. However the diffuse magnetic neutron scattering seen in powder measurements has previously been fitted by 2D Warren-type correlations. Using neutron spectroscopy, we show that paramagnetic fluctuations persist up to $\sim$25 meV above TN= 65 K. This is comparable to the incident energy of typical diffractometers, a…
Magnetism in Polyoxometalates: Anisotropic Exchange Interactions in the Co Moiety of [Co3W(D2O)2(ZnW9O34)2]12−—A Magnetic and Inelastic Neutron Scatt…
2002
The ground-state properties of a Co moiety encapsulated in a polyoxometalate anion were investigated by combining measurements of specific heat, magnetic susceptibility, and low-temperature magnetization with a detailed inelastic neutron scattering (INS) study on a fully deuterated polycrystalline sample of Na12[Co3W(D2O)2(ZnW9O34)2]⋅40 D2O (Co3). The ferromagnetic Co3O14 cluster core consists of three octahedrally oxo-coordinated CoII ions. According to the single-ion anisotropy and spin–orbit coupling of the octahedral CoII ions, the appropriate exchange Hamiltonian to describe the ground-state properties of the Co3 spin cluster is anisotropic and is expressed as ℋ=−2Σ(JŜ1αŜ2α+JŜ2αŜ3α), w…
Decoupling lattice and magnetic instabilities in frustrated CuMnO$_2$
2021
The $A$MnO$_{2}$ delafossites ($A$=Na, Cu), are model frustrated antiferromagnets, with triangular layers of Mn$^{3+}$~spins. At low temperatures ($T_{N}$=65 K), a $C2/m \rightarrow P\overline{1}$ transition is found in CuMnO$_2$, which breaks frustration and establishes magnetic order. In contrast to this clean transition, $A$=Na only shows short-range distortions at $T_N$. Here we report a systematic crystallographic, spectroscopic, and theoretical investigation of CuMnO$_2$. We show that, even in stoichiometric samples, non-zero anisotropic Cu displacements co-exist with magnetic order. Using X-ray/neutron diffraction and Raman scattering, we show that high pressures acts to decouple the…
Magnetic polyoxometalates: anisotropic exchange interactions in the moiety of [(NaOH2)Co3(H2O)(P2W15O56)2]17-.
2005
The magnetic exchange interactions in a C0(3)(11) moiety encapsulated in Na(17) [(NaOH(2))Co(3)(H(2)O)(P(2)W(15)O(56))(2)] (NaCo(3)) were studied by a combination of magnetic measurements (magnetic susceptibility and low-temperature magnetization), with a detailed Inelastic Neutron Scattering (INS) investigation. The novel structure of the salt was determined by X-ray crystallography. The ferromagnetic Co(3)O(14) triangular cluster core consists of three octahedrally oxo-coordinated Co(II) ions sharing edges. According to the single-ion anisotropy and spin-orbit coupling usually assumed for octahedral Co(II) ions, the appropiate exchange Hamiltonian to describe the ground-state properties o…