On bistability in molecular systems: Photomagnetic studies of inorganic complexes

Photo‐induced effects have been detected by magnetic measurements, Mössbauer spectroscopy and reflectivity. The LIESST effect has been achieved in the spin‐crossover system [Fe_xCo_1-x(btr)₂(NCS)₂]·H₂O. We investigated the purely photo‐induced magnetism of a Prussian Blue analogue Rb_0.52Co[Fe(CN)₆]_0.84, 2.31 H₂O, involving an optical electron transfer from Fe^II to Co^III. Inherent aspects of photomagnetic experiments are described: bulk and surface effects, magnetic and electronic metastabilities of the photo‐excited state.     

Quantum-tunneling-induced Kondo effect in single molecular magnets

We consider transport through a single-molecule magnet strongly coupled to metallic electrodes. We demonstrate that, for a half-integer spin of the molecule, electron and spin tunneling cooperate to produce both quantum tunneling of the magnetic moment and a Kondo effect in the linear conductance. The Kondo temperature depends sensitively on the ratio of the transverse and easy-axis anisotropies in a nonmonotonic way. The magnetic symmetry of the transverse anisotropy imposes a selection rule on the total spin for the occurrence of the Kondo effect which deviates from the usual even-odd alternation.     

Inverse Faraday effect in crystals of molecular magnets

The occurrence of constant magnetization in an initially nonmagnetized crystal of Mn₁₂-Ac magnetic molecules under the action of a circularly polarized THz electromagnetic wave has been considered.     

稀土元素三角格子体系中的阻挫磁性与量子涨落

稀土元素三角格子阻挫体系在近几年受到了广泛的关注,稀土元素中存在较强的自旋轨道耦合作用,容易形成各向异性的磁相互作用,结合复杂的晶体场结构,可以产生很多新奇的物理性质,实现包括量子自旋液体、内禀量子伊辛磁体和隐藏序在内的一系列新奇量子态。文章以最近的中子散射研究为例,介绍稀土元素三角格子体系中的新奇磁关联与量子涨落现象。     

The magnetic memory effect in fullerene-containing single molecular magnets

We studied the influence of fullerenes on the properties of molecular magnets of the family of oxocarboxylate clusters of Mn₁₂. A strong asymmetry in the hysteresis loop was observed for the first time. As opposed to the well-known effect of the displacement of a hysteresis loop along the magnetic field axis (the phenomenon of exchange bias), the observed effect of magnetic memory resides in the displacement along the vertical axis.     

The evaluation of overlap and Coulomb integrals in complexes with rare-earth or transition-metal central ions

Tables are given to enable effective algorithms to be formed for computer calculation of the overlap and Coulomb integrals with Slater-type orbitals in complexes with rare-earth or transition-metal central ions.     

Self-ordered dendrimers based on multi-octupolar ruthenium complexes for quadratic nonlinear optics

A quasi-optimized supramolecular octupolar ordering has been achieved in a metallodendrimer made of several ruthenium tris-bipyridine complexes displaying high nonlinear optical efficiency. This acentric organization is evidenced by Harmonic Light scattering at 1.9 μm, where a coherent second harmonic emission from each dendrimer unit is compared to the fully incoherent harmonic signal from a disordered linear polymer containing the same nonlinear complexes. These results show the interest of a controlled coordination strategy to build supramolecules and dendritic structures, with promising perspectives towards nanoscale applications in photonics.     

Magnetostriction of dilute rare-earth bismuthides: The effect of non-S-state ions versus “S-state” ions

Shape magnetostriction measurements along the [001] direction were carried out for dilute rare-earth bismuthides; LaBi: R (R = Ce, Sm, Gd, Tb, Er) and the antimonide LaSb: Gd. The magnetostriction of LaBi: Ce and LaBi: Sm reveal the “reverse magnetostriction” phenomenon, enabling us to extract an overall crystalline field splitting of 12 K for the former compound. The magnetostriction of LaBi: Gd and LaSb: Gd which are significantly larger than that of the “pure” hosts, can be explained by a modified version of a model previously suggested by us. The fitting procedure yields magnetoelastic coupling constants for LaSb: Gd and LaBi: Gd which has the correct sign and magnitude according to existing theories.     

Positron annihilation study of ordering processes in rare-earth cobalt permanent magnets

The ordering process in 1/5 and in 2/17 Sm-Co permanent magnets was followed by positron annihilation lifetime and Doppler broadening measurements. No correlation between magnetic hardness and positron annihilation parameters was found.     

The effect of Ce3+ ions on the spectral and decay characteristics of luminescence phosphate-borate glasses doped with rare-earth ions

The luminescent characteristics of Li₂O-B₂O₃-P₂O₅-CaF₂ (LBPC) glasses doped with Gd³⁺ and Tb³⁺ ions and codoped with Ce³⁺ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce³⁺ and Gd³⁺ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (⁶ P _J → ⁸ S _7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce³⁺ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed.     

Spatial correlations of rare-earth ions in mixed-valence systems

An effective interaction between 4?-occupied rare-earth ions arises from the scattering of the conduction electrons with the localized 4?-electrons. Due to the space dependence of this interaction the ground state energy depends on the distribution of the localized 4?-electrons. We discuss the possibility of clustering and ordering in simple cases.     

Fluorescence of rare-earth ions in dirty displacive ferroelectrics

The phase transition of ferroelectric Sr_1?xBa_xNb₂O₆ was studied by measuring the fluorescence emitted from the rare-earth ions doped as a probe. The fluorescence spectral width and the wavelength showed singular behavior around the transition temperature. The samples possess a diffuse transition with characteristic optical properties near the inflection point of the temperature-dependence curve of the spontaneous polarization.     

Applications and functions of rare-earth ions in perovskite solar cells

The emerging perovskite solar cells have been recognized as one of the most promising new-generation photovoltaic technologies owing to their potential of high efficiency and low production cost. However, the current perovskite solar cells suffer from some obstacles such as non-radiative charge recombination, mismatched absorption, light induced degradation for the further improvement of the power conversion efficiency and operational stability towards practical application. The rare-earth elements have been recently employed to effectively overcome these drawbacks according to their unique photophysical properties. Herein, the recent progress of the application of rare-earth ions and their functions in perovskite solar cells were systematically reviewed. As it was revealed that the rare-earth ions can be coupled with both charge transport metal oxides and photosensitive perovskites to regulate the thin film formation, and the rare-earth ions are embedded either substitutionally into the crystal lattices to adjust the optoelectronic properties and phase structure, or interstitially at grain boundaries and surface for effective defect passivation. In addition, the reversible oxidation and reduction potential of rare-earth ions can prevent the reduction and oxidation of the targeted materials. Moreover, owing to the presence of numerous energetic transition orbits, the rare-earth elements can convert low-energy infrared photons or high-energy ultraviolet photons into perovskite responsive visible light, to extend spectral response range and avoid high-energy light damage. Therefore, the incorporation of rare-earth elements into the perovskite solar cells have demonstrated promising potentials to simultaneously boost the device efficiency and stability.     

The effect of doped ions on single-molecule magnets of the Mn12-Ac family

This paper investigates the single-molecule magnets of pure and Cr/Fe-doped Mn12-Ac. The components of the mixed crystals are identified by AC susceptibility technique. The ground-state spin and anisotropy parameters of doped Mn12-Ac are obtained： （i） MnllCr-Ac （S=19/2, D=0.62K, B=0.0009K, A=63K）, and （ii） Mn11Fe-Ac （S=21/2, D=0.39 K, B=0.001 K, △=55 K）. The single-ion origin of the magnetic anisotropy is discussed.     

Influence of rare-earth ions on the dielectric response in stillwellite glasses

Experimental spectra of the dielectric response function of glasses with the composition LnBGeO₅ (Ln = La, Pr, Tb, Er, Sm) in the terahertz and infrared ranges are compared. Absorption bands are identified, and their contributions to permittivity are established. The contours of the boson peak and the dependence of the dielectric loss on the type of rare-earth ion are determined.