We report on coherent manipulation of electron spins in an antiferromagnetically coupled spin triangle {Cu3-X} (X=As, Sb) impregnated in freestanding nanoporous silicon (NS) by using 240 GHz ...microwave pulses. Rabi oscillations are observed and the spin coherence time is found to be T(2)=1066 ns at 1.5 K. This demonstrates that the {Cu3-X}:NS hybrid material provides a promising scheme for implementing spin-based quantum gates. By measuring the spin relaxation times of samples with different symmetries and environments we give evidence that a spin chirality is the main decoherence source of spin triangle molecules.
The high-field magnetic properties and magnetic order of the gem mineral green dioptase Cu6 Si6 O 18 ⋅ 6 H2O have been studied by means of single-crystal neutron diffraction in magnetic fields up ...to 21 T and magnetization measurements up to 30 T. In zero field, the Cu2+ moments in the antiferromagnetic chains are oriented along the c axis with a small off-axis tilt. For a field applied parallel to the c axis, the magnetization shows a spin-flop-like transition at B ∗ = 12.2 T at 1.5 K. Neutron diffraction experiments show a smooth behavior in the intensities of the magnetic reflections without any change in the periodicity of the magnetic structure. Bulk and microscopic observations are well described by a model of ferromagnetically coupled antiferromagnetic X X Z spin1/2 chains, taking into account a change of the local easy-axis direction. We demonstrate that the magnetic structure evolves smoothly from a deformed Néel state at low fields to a deformed spin-flop state in a high field via a strong crossover around B ∗ . The results are generalized for different values of interchain coupling and spin anisotropy.
We report high resolution single crystal x-ray diffraction measurements of the frustrated pyrochlore magnet Tb2Ti2O7, collected using a novel low temperature pulsed magnet system. This instrument ...allows characterization of structural degrees of freedom to temperatures as low as 4.4 K, and in applied magnetic fields as large as 30 T. We show that Tb2Ti2O7 manifests intriguing structural effects under the application of magnetic fields, including strongly anisotropic giant magnetostriction, a restoration of perfect pyrochlore symmetry in low magnetic fields, and ultimately a structural phase transition in high magnetic fields. It is suggested that the magnetoelastic coupling thus revealed plays a significant role in the spin liquid physics of Tb2Ti2O7 at low temperatures.
The ferrimagnetic spinel MnCr2 S4 shows a variety of magnetic-field-induced phase transitions owing to bond frustration and strong spin-lattice coupling. However, the site-resolved magnetic ...properties at the respective field-induced phases in high magnetic fields remain elusive. Our soft x-ray magnetic circular dichroism studies up to 40 T directly evidence element-selective magnetic-moment reorientations in the field-induced phases. The complex magnetic structures are further supported by entropy changes extracted from magnetocaloric-effect measurements. Moreover, thermodynamic experiments reveal an unusual tetracritical point in the H − T phase diagram of MnCr2 S4 due to strong spin-lattice coupling.
Cyanide-bridged Fe-Co complex Fe(Tp)(CN)
3
2
Co(bpe)⋅5H
2
O (
1
⋅5H
2
O; Tp = hydro-tris(pyrazolyl)borate; bpe = 1,2-bis(4-pyridyl)ethane) shows temperature- and light- induced metal-to-metal charge ...transfer (MMCT) involving spin state changes between magnetic
(HS = high spin, LS = low spin) state and nonmagnetic
state, while the dehydrated material
1
does not show any MMCT and holds
state. We have investigated the magnetic properties of each spin state in
1
and
1
⋅5H
2
O by means of magnetization and ESR measurement under pulsed high magnetic field. At low temperature below
T
N
, in both
1
and
1
⋅5H
2
O, the saturation magnetization in the induced ferromagnetic phase is well explained by
S
and
g
values derived from the magnetic susceptibility study. In the ESR of
1
, we observed characteristic modes corresponding to a spin excitation in the induced ferromagnetic phase where its temperature dependence shows an evolution of spin correlation in the
state at low temperature. We further found that the similar ESR modes grow in the light-induced state of
1
⋅5H
2
O. The results strongly suggest that the light-induced magnetization in
1
⋅5H
2
O is driven by a light-induced MMCT, which involves transition of spin multiplicity from the nonmagnetic
to the magnetic
pair.
In the last decade, extensive investigation has been done on the bacterial degradation of dioxins and its related compounds, because this class of chemicals is highly toxic and has been widely ...distributed in the environment. These studies have revealed the primary importance of a novel dioxygenation reaction, called angular dioxygenation, in the aerobic bacterial degradation pathway of dioxin. Accompanied by the electron transport proteins, Rieske nonheme iron oxygenase catalyzes the incorporation of oxygen atoms to the ether bond-carrying carbon (the angular position) and an adjacent carbon, resulting in the irreversible cleavage of the recalcitrant aryl ether bond. The 2,2′,3-trihydroxybiphenyl or 2,2′,3-trihydroxydiphenyl ether derivatives formed are degraded through meta cleavage. In addition to the degradation system of dibenzofuran and dibenzo-p-dioxin (the nonchlorinated model compounds of dioxin), those of fluorene and carbazole were shown to function in dioxin degradation. Some dioxin degradation pathways have been studied biochemically and genetically. In addition, feasibility studies have shown that some dioxin-degrading strains can function in actual dioxin-contaminated soil. These studies provide useful information for the establishment of a bioremediation method for dioxin contamination. This review summarizes recent progress on molecular and biochemical bases of the bacterial aerobic degradation of dioxin and related compounds.
We report bulk magnetization, and elastic and inelastic neutron scattering measurements under an external magnetic field H on the weakly coupled distorted kagome system, Cu2(OD)3Cl. Our results show ...that the ordered state below 6.7 K is a canted antiferromagnet and consists of large antiferromagnetic ac components and smaller ferromagnetic b components. By first-principles calculations and linear spin wave analysis, we present a simple spin Hamiltonian with nonuniform nearest neighbor exchange interactions resulting in a system of coupled spin trimers with a single-ion anisotropy that can qualitatively reproduce the spin dynamics of Cu2(OD)3Cl.
PDF
