Measurement of storage time, estimation of ion number and study of absorption line profile in a Paul trap

Europium (Eu⁺) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu⁺ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions. The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both experimentally and theoretically.     

Torsional strain of TaS3 whiskers on the charge-density wave depinning

We find that an electric current I exceeding the threshold value results in torsional strain of o-TaS3 samples with one contact freely suspended. The rotation angle deltavarphi of the free end achieves several degrees and exhibits hysteresis as a function of I. The sign of deltavarphi depends on the I polarity; a polar axis along the conducting chains (the c axis) is pointed out. We associate the effect with surface shear of the charge-density wave (CDW) coupled to the crystal shear. The current-induced torsional strain could be treated in terms of enormous piezoelectric coefficients (>10(-4) cm/V) corresponding to shear. In essence, TaS3 appears to be a ready torsional actuator based on the unique intrinsic property of the CDW.     

Correction: Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity

After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5.     

Four contact electrical measurements on the anisotropic high-Tc superconductors: voltage reversals

We describe three mechanisms for the anomalous voltage reversals which are occasionally observed during four contact current-voltage measurements on the high temperature superconductors. Voltage reversals have been frequently observed for whiskers of the bismuth strontium calcium copper oxide (BSSCO) compounds, and we describe measurements made on high quality whiskers of the 2:2:1:2 and 2:2:2:3 phases. A simple model based on extreme anisotropy plus offset contacts can explain the gross features of four contact measurements in the ohmic flux-flow regime, but not the wealth of reversal phenomena found for the IVVI configuration in the lower temperature irreversibility region.     

Peculiarities of carrier scattering at the boundary of a normal metal and a quasi-one-dimensional conductor with a charge-density wave

Nonlinear effects at the interface between a normal metal and the quasi-one-dimensional conductor with a charge-density wave K_0.3MoO₃ are investigated experimentally. It is found that the scattering of the normal carriers with energy E less than the Peierls gap Δ_p gives rise to an excess resistance of the N-CDW boundary. The character of the scattering is similar to Andreev reflection. In contrast to superconductors, however, the sign of the charge of the reflected particle does not change. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 4, 259–264 (25 August 1996)     

Shapiro steps in the torsion of a quasi-one-dimensional conductor TaS<Subscript>3</Subscript>

Features have been observed in the current dependences of the torsion angle, φ(I), for samples of a quasi-one-dimensional conductor TaS₃ irradiated by a high-frequency (HF) field. The features appear at the same current values as the Shapiro steps on the current-voltage characteristics, i.e., correspond to the synchronization of the motion of a charge-density wave (CDW) by the HF field. The shape of the features in the φ(I) dependences indicates a decrease in the inhomogeneous deformation of the CDW under the synchronization conditions. The investigation of torsion appears to be a highly sensitive method for determining the spatial coherence of the CDW.     

Local spectroscopy of carrier reflection at the interface between a normal metal and the Peierls conductor K0.3MoO3

The nature of carrier reflection from a normal metal-Peierls conductor interface is clarified by studying the characteristics of point contacts formed with an intermediate metallic layer sputtered onto the (010) face of K_0.3MoO₃ crystals (injection along the chains) or the face (injection perpendicular to the chains). In the Peierls state, for bias voltages eV smaller than the Peierls gap Δ_P, an excess differential resistance is observed with a local minimum at V=0. The magnitude of the excess resistance is proportional to a ²/d ², where a is the contact diameter and d is the thickness of the metal film. The excess resistance is much higher for injection along the chains than for injection perpendicular to them. A comparative analysis of the data for different injection directions indicates that the dominant contribution to the excess resistance for injection along the chains is from normal reflection of carriers without changes in the sign of their charge and with a momentum transfer 2p _F to the condensate of electron-hole pairs carried away from the interface. Zh. éksp. Teor. Fiz. 113, 1830–1842 (May 1998)     

Nonlinear conductivity of quasi-one-dimensional layered compound TiS3

The crystal structure and transport properties of TiS₃ whiskers in the plane of layers (ab) have been studied. Maxima of the logarithmic derivative of resistance, dln R/d(1/T), are observed at 17, 60 and 120 K both along and across the chains. Strong nonlinearity of the current–voltage characteristics has been revealed in both directions. Nonlinear conductivity along the chains is observed up to T=60 K, while in the transverse direction it is observed up to T=130 K. The results indicate possible phase transitions of electrons to collective states, probably, charge density waves.