N. Yu. Shitsevalova

Linear and nonlinear low-frequency electrodynamics of surface superconducting states in an yttrium hexaboride single crystal

We report the low-frequency and tunneling studies of yttrium hexaboride single crystal. Ac susceptibility at frequencies 10 - 1500 Hz has been measured in parallel to the crystal surface DC felds, H0. We found that in the DC feld H0 > Hc2 DC magnetic moment completely disappears while the ac response exhibited the presence of superconductivity at the surface. Increasing of the DC field from Hc2 revealed the enlarging of losses with a maximum in the feld between Hc2 and Hc3. Losses at the maximum were considerably larger than in the mixed and in the normal states. The value of the DC field, where loss peak was observed, depends on the amplitude and frequency of the ac feld. Close to Tc this peak shifts below Hc2 which showed the coexistence of surface superconducting states and Abrikosov vortices. We observed a logarithmic frequency dependence of the in-phase component of the susceptibility. Such frequency dispersion of the inphase component resembles the response of spin-glass systems, but the out-of-phase component also exhibited frequency dispersion that is not a known feature of the classic spin-glass response. Analysis of the experimental data with Kramers-Kronig relations showed the possible existence of the loss peak at very low frequencies ( Hc2.

Antiferro-quadrupole resonance in CeB6

We report experimental observation of a new type of magnetic resonance caused by orbital ordering in a strongly correlated electronic system. Cavity measurements performed on CeB 6 single crystals in a frequency range 60-100 GHz show that a crossing of the phase boundary T Q (B) between the antiferro-quadrupole and paramagnetic phases gives rise to development at T< T Q (B) of a magnetic resonance. The observed mode is gapless and correspond to g-factor 1.62.

Lattice dynamics and magneto-elastic coupling in Kondo-insulator YbB12

Lattice dynamics and magneto-elastic coupling effects have been studied in the Kondo insulator YbB12 by means of inelastic neutron scattering. The analysis of the phonon density of states, dispersion, and symmetry properties is presented in connection with a possible magneto-elastic coupling. Manifestation of such effects was found for the phonons corresponding to the vibrations of Yb atoms.

Magnetic resonance in cerium hexaboride caused by quadrupolar ordering

Abstract Experimental evidence of the magnetic resonance in the antiferro-quadrupole phase of CeB 6 is reported. We have shown that below orbital ordering temperature a new magnetic contribution emerges and gives rise to the observed resonant phenomenon.

Suppression of superconductivity inLuxZr1−xB12: Evidence of static magnetic moments induced by nonmagnetic impurities

Based on low temperature resistivity, heat capacity and magnetization investigations we show that the unusually strong suppression of superconductivity in Lu

Magnetic field dependence of the neutron spin resonance in CeB 6

_x

Doping-induced redistribution of magnetic spectral weight in substituted hexaborides Ce

Zr

_{1-x}

_{1-x}

La

B

_x

_{12}