相关论文: Different Evolution of Intrinsic Gap in Kondo Semi…

We have studied the effect of Lu substitution on the spin dynamics of the Kondo insulator YbB12 to clarify the origin of the spin-gap response previously observed at low temperature in this material. Inelastic neutron spectra have been…

Optical conductivity [$\sigma(\omega)$] of the Kondo semiconductor YbB$_{12}$ has been measured over wide ranges of temperature ($T$=8$-$690 K) and photon energy ($\hbar \omega \geq$ 1.3 meV). The $\sigma(\omega)$ data reveal the entire…

We discuss the evolution of topological states and their orbital textures in the mixed valence compounds SmB6 and YbB6 within the framework of the generalized gradient approximation plus onsite Coulomb interaction (GGA+U) scheme for a wide…

A new LDA+U band calculation is performed on the Kondo insulator material YbB$_{12}$ and an energy gap of about 0.001Ryd is obtained. Based on this, a simple tight-binding model with 5d$\epsilon$ and 4f $\Gamma_8$ orbitals on Yb atoms and…

The spin dynamics of mixed-valence YbB12 has been studied by inelastic neutron scattering on a high-quality single crystal. In the Kondo-insulating regime realized at low temperature, the spectra exhibit a spin-gap structure with two sharp,…

SmB6 is a promising candidate for topological Kondo insulator. In this letter, we report ultrafast carrier dynamics of SmB6. Two characteristic temperatures: T1=100 K and T2= 20 K are observed. T1 corresponds to the opening of the f-d…

SmB6 is a proposed topological Kondo insulator where the presence of topological nontriviality can be tuned by variations in the Sm valence. Experimentally, Sm valence can be changed by tuning stoichiometry of SmB6. We show that Raman…

Optical reflectivity experiments have been conducted on single crystals of the Kondo insulator YbB_12 in order to obtain its optical conductivity, \sigma(\omega). Upon cooling below 70 K, a strong supression of \sigma(\omega) is seen in the…

In heavy fermions the relaxation dynamics of photoexcited carriers has been found to be governed by the low energy indirect gap, E$_{g}$, resulting from hybridization between localized moments and conduction band electrons. Here, carrier…

A detailed low-energy electronic structure of a Kondo insulator YbB$_{12}$ was revealed by a synergetic combination of ultrahigh-resolution laser photoemission spectroscopy (PES) and time-resolved PES. The former confirmed a 25-meV…

The Kondo insulator SmB$_6$ has long been known to display anomalous transport behavior at low temperatures, T$<5$ K. In this temperatures range, a plateau is observed in the dc resistivity, contrary to the exponential divergence expected…

Defying the traditional classification into metals and insulators, several materials simultaneously display metallic thermal properties and insulating electric behaviour, as if they hosted quasiparticles carrying entropy but not charge.…

Earlier studies on the Kondo insulator SmB6 reveal the presence of a bulk Kondo insulating gap between 30 - 50 K, and the emergence of a conducting surface state only below 4 K. Here, we compare the two-coil mutual inductance pick-up…

SmB$_6$, known to be a Kondo insulator, has received intense scrutiny in recent years due to its paradoxical experimental signatures: while some quantities show an insulating behavior, others point to a metallic state. This has led to the…

We use scanning tunneling microscopy to investigate the (001) surface of cleaved SmB6 Kondo insulator. Variable temperature dI/dV spectroscopy up to 60 K reveals a gap-like density of state suppression around the Fermi level, which is due…

Kondo insulators (KIs) are strongly correlated materials in which the interactions between 4f and conduction electrons lead to a hybridization gap opening at low temperature 1-2. SmB6 is a typical KI, but its resistivity does not diverge at…

Recent studies suggest that an exemplary Kondo insulator SmB6 belongs to a new class of topological insulators (TIs), in which non-trivial spin-polarized metallic states emerge on surface upon the formation of Kondo hybridization gap in the…

The recent rekindling of interest in the mixed valent Kondo insulator SmB$_{6}$ as candidate for a first correlated topological insulator has resulted in a wealth of new experimental observations. In particular, angle-resolved photoemission…

We present a comprehensive optical study of the narrow gap $FeSb_2$ semiconductor. From the optical reflectivity, measured from the far infrared up to the ultraviolet spectral range, we extract the complete absorption spectrum, represented…

Topological insulators give rise to exquisite electronic properties due to their spin-momentum locked Dirac-cone-like band structure. Recently, it has been suggested that the required opposite parities between valence and conduction band…