Sai Mu

Surface-induced spin state locking of the [Fe(H2B(pz)2)2(bipy)] spin crossover complex

Temperature- and coverage-dependent studies of the Au(1 1 1)-supported spin crossover Fe(II) complex (SCO) of the type [Fe(H2B(pz)2)2(bipy)] with a suite of surface-sensitive spectroscopy and microscopy tools show that the substrate inhibits thermally induced transitions of the molecular spin state, so that both high-spin and low-spin states are preserved far beyond the spin transition temperature of free molecules. Scanning tunneling microscopy confirms that [Fe(H2B(pz)2)2(bipy)] grows as ordered, molecular bilayer islands at sub-monolayer coverage and as disordered film at higher coverage. The temperature dependence of the electronic structure suggest that the SCO films exhibit a mixture of spin states at room temperature, but upon cooling below the spin crossover transition the film spin state is best described as a mix of high-spin and low-spin state molecules of a ratio that is constant. This locking of the spin state is most likely the result of a substrate-induced conformational change of the interfacial molecules, but it is estimated that also the intra-atomic electron-electron Coulomb correlation energy, or Hubbard correlation energy U, could be an additional contributing factor.

First-principles microscopic model of exchange-driven magnetoelectric response with application to Cr 2 O 3

The exchange-driven contribution to the magnetoelectric susceptibility

Spectral signatures of thermal spin disorder and excess Mn in half-metallic NiMnSb

\hat\alpha

The Electronic Structure Signature of the Spin Cross-Over Transition of [Co(dpzca)2]

is formulated using a microscopic model Hamiltonian coupling the spin degrees of freedom to lattice displacements and electric field, which may be constructed from first-principles data. Electronic and ionic contributions are sorted out, and the latter is resolved into a sum of contributions from different normal modes. If intrasublattice spin correlations can be neglected, the longitudinal component

Effect of substitutional doping on the Néel temperature of Cr 2 O 3

\alpha_\parallel

Complexities in the Molecular Spin Crossover Transition

becomes proportional to the product of magnetic susceptibility and sublattice magnetization in accordance with Rados phenomenological model. As an illustration, the method is applied to analyze the temperature dependence of the longitudinal magnetoelectric susceptibility of Cr

Strategies for increasing the Néel temperature of magnetoelectric Fe2TeO6.

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MAGNETOELECTRIC CHROMIA HAVING INCREASED CRITICAL TEMPERATURE

O

Aspects of bulk and surface magnetism of magnetoelectric Fe

_3

_2

using first-principles calculations and the quantum pair cluster approximation for magnetic thermodynamics. A substantial electronic contribution is found, which is opposite to the ionic part. The sensitivity of the results to the Hubbard