Related papers: Coexisting Kondo hybridization and itinerant f-ele…
We report a systematic study of the $5d$-electron-doped system Ce(Fe$_{1-x}$Ir$_x$)$_2$Al$_{10}$ ($0 \leq x \leq 0.15$). With increasing $x$, the orthorhombic $b$~axis decreases slightly while accompanying changes in $a$ and $c$ leave the…
Strongly correlated materials are characterized by the presence of electron-electron interactions in their electronic structure. They often have remarkable properties and transitions between competing phases of very different electronic and…
Formation of magnetically ordered state in the Kondo lattices is treated within the degenerate $s-f$ exchange and Coqblin-Schrieffer models. The Kondo renormalizations of the effective coupling parameter, magnetic moment and spin excitation…
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…
The underscreened Kondo lattice consisting of a single twofold degenerate conduction band and a CEF split 4f-electron quasi-quartet has non-conventional quasiparticle dispersions obtained from the constrained mean-field theory. An…
Hydrogen in metals has attracted much attention for a long time from both basic scientific and technological points of view. Its electronic state has been investigated in terms of a proton embedded in the electron gas mostly by the local…
We present a phenomenological solution of the Kondo lattice that is derived from an analysis of the bulk specific heat and spin susceptibility of the heavy electron superconductor CeCoIn5. We find that below a crossover temperature…
Correlated interaction between dilute localized impurity electrons with the itinerant host conduction electrons in metals gives rise to the conventional many-body Kondo effect below sufficiently low temperature. In sharp contrast to these…
The phase transition to ferromagnetic order in itinerant ferromagnetic superconductor UGe$_2$ as function of pressure shows change of phase transition order. At low temperature and high pressure the transition is of first order and at…
We have studied electronic and magnetic properties of the K0.8Fe1.6Se2 superconductor by x-ray absorption and emission spectroscopy. Detailed temperature dependent measurements alongwith a direct comparison with the binary FeSe system have…
We utilize terahertz time domain spectroscopy to investigate thin films of the heavy fermion compound SmB6, a prototype Kondo insulator. Temperature dependent terahertz (THz) conductivity measurements reveal a rapid decrease in the Drude…
The magneto-elastic mechanism of development of the first order type instability at the phase transition to the ferromagnet state in itinerant ferromagnet-superconductor UGe2 is discussed. The particular property of this material is the…
By means of a specific heat ($C$) and electrical resistivity ($\varrho$) study, we give evidence of a pronounced Fermi liquid (FL) behavior with sizable mass renormalization, $m^{\ast}/m = 30$, up to unusually high temperatures $\sim$70 K…
Superconductivity in three dimensions is almost universally governed by Ginzburg-Landau mean field theory, with critical fluctuations typically confined to within a few percent of the transition temperature ($T_{\rm c}$). We report that the…
We review our recent studies on ferromagnetic superconductors, UGe2, URhGe and UCoGe, together with the ferromagnetic quantum criticality and paramagnetic singularity on the Ising 5f-itinerant system UCoAl. Thanks to the variety of ordered…
Solids with strong electron correlations generally develop exotic phases of electron matter at low temperatures. Among such systems, the heavy-fermion semi-metal URu2Si2 presents an enigmatic transition at To = 17.5 K to a `hidden order'…
Heavy fermion systems represent one of the paradigmatic strongly correlated states of matter. They have been used as a platform for investigating exotic behavior ranging from quantum criticality and non-Fermi liquid behavior to…
I present the results of first principles calculations of the electronic structure and magnetic interactions for the recently discovered superconductor YFe$_2$Ge$_2$ and use them to identify the nature of superconductivity and quantum…
The existence of multiple energy scales is regarded as a signature of the Kondo breakdown mechanism for explaining the quantum critical behavior of certain heavy fermion compounds, like YbRh$_{2}$Si$_{2}$. The nature of the intermediate…
The novel spin-triplet superconductor candidate UTe2 was discovered only recently at the end of 2018 and attracted enormous attention. We review key experimental and theoretical progress which has been achieved in different laboratories.…