相关论文: Novel Valence Transition in Elemental Metal Europi…

Valence transitions in strongly correlated electron systems are caused by orbital hybridization and Coulomb interactions between localized and delocalized electrons. The transition can be triggered by changes in the electronic structure and…

In order to probe the changes in the valence state and magnetic properties of Eu metal under extreme pressure, x-ray absorption near-edge spectroscopy, x-ray magnetic circular dichroism and synchrotron M\"ossbauer spectroscopy experiments…

We present results of the magnetic susceptibility on high-quality single crystals of EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ for Ge concentrations 0 $\leq x \leq$ 0.105 performed under varying hydrostatic (He-gas) pressure 0 $\leq p \leq$ 0.5 GPa.…

We present results of hard X-ray angle-resolved photoemission spectroscopy and photoemission diffraction measurements performed on high-quality single crystals of the valence transition compound EuPd$_2$Si$_2$ for temperatures 25~K $\leq$ T…

High pressure x-ray diffraction up to 30 GPa and resonant emission x-ray spectroscopy and partial fluorescence yield x-ray absorption spectroscopy up to 52 GPa were used to study how the structural and electronic properties of UTe$_2$…

Superconductivity can be realized in Eu-containing pnictides by application of chemical (internal) and physical (external) pressure, the intrinsic physical mechanism of which attracts much attention in physics community. Here we present the…

We have studied crystal structure, magnetism and electric transport properties of a europium fulleride Eu6C60 and its Sr-substituted compounds, Eu6-xSrxC60. They have a bcc structure, which is an isostructure of other M6C60 (M represents an…

The rare earth metal praseodymium (Pr) transforms from the d-fcc crystal structure (Pr-III) to {$\alpha$}-U one (Pr-IV) at 20 GPa with a large volume collapse (${\rm\Delta} V/V$ = 0.16), which is associated with the valence change of the Pr…

Synchrotron x-ray diffraction experiments have been carried out on Eu metal at ambient temperature to pressures as high as 92 GPa (0.92 Mbar). Following the well-known bcc-to-hcp transition at 12 GPa, a mixed phase region is observed from…

Unusual phases and phase transitions are seen at the magnetic-nonmagnetic boundary in Ce, Eu and Yb-based compounds. EuNi$_2$P$_{2}$ is a very unusual valence fluctuating Eu system, because at low temperatures the Eu valence stays close to…

We present results of magnetic susceptibility and thermal expansion measurements performed on high-quality single crystals of EuPd$_2$(Si$_{1-x}$Ge$_x$)$_2$ for 0 $\leq$ x $\leq$ 0.2 and temperatures 2 K $\leq T \leq$ 300 K. Data were taken…

In solid-state compounds, the valence of europium can sometimes be mixed -- which is especially favored in structures with several positions for the europium atoms. In this work, we study the Eu-based intermetallic noncentrosymmetric system…

The pressure-dependent relation between Eu valence and lattice structure in model compound EuO is studied with synchrotron-based x-ray spectroscopic and diffraction techniques. Contrary to expectation, a 7% volume collapse at $\approx$ 45…

The study of Eu intermetallic compounds has allowed the exploration of valence fluctuations and transitions in 4f electron systems. Recently, a Eu$_2$Pt$_6$Al$_{15}$ phase synthesized by arc-melting followed by a thermal treatment was…

We study the mixed valence transition ($T$$_{v}$ $\sim$80 K) in EuNi$_{2}$(Si$_{0.2}$Ge$_{0.8}$)$_{2}$ using Eu 3$d-4f$ X-ray absorption spectroscopy (XAS) and resonant photoemission spectroscopy (RESPES). The Eu$^{2+}$ and Eu$^{3+}$ main…

$^{151}$Eu M\"ossbauer spectroscopy shows that yttrium substitution in mixed-valent $\rm EuPd_3S_4$ drives the initial 50:50 mix of Eu$^{3+}$ and Eu$^{2+}$ towards pure Eu$^{2+}$, whereas lanthanum substitution has the opposite effect, but…

Neutron diffraction experiments on TmTe at pressures up to 7 GPa are reported. The semiconductor-to-metal transition occurring at 2 GPa in this compound is accompanied by the appearance of strong ferromagnetic exchange interactions…

Valence instability is a key ingredient of the unusual properties of f electron materials, yet a clear understanding is lacking as it involves a complex interplay between f electrons and conduc- tion states. Here we propose a unified…

Divalent Eu (4f7, J=7/2) possesses a strong local magnetic moment which suppresses superconductivity. Under sufficient pressure it is anticipated that Eu will become trivalent (4f6, J=0) and a weak Van Vleck paramagnet, thus opening the…

Europium, one of the rare earth elements, exhibits +2 and +3 valence states and has been widely used for magnetic modification of materials. Based on density functional theory calculations, we predict the 2D EuBr/graphene heterojunctions to…