Aharonov-Bohm effect for electrons on a liquid-helium surface

A method for obtaining finite electronic systems on a liquid-helium surface is proposed. If a thin film of liquid helium lies above a bottom capacitor plate made in the form of metal rings connected with one another, then electrons will accumulate in potential troughs near these rings. The purity of the helium surface, i.e., the absence of impurities and pinning centers on it, affords an excellent opportunity for investigating the Aharonov-Bohm effect in an ideal ring of a Wigner crystal and a Luttinger liquid Pis’ma Zh. éksp. Teor. Fiz. 67, No. 6, 410–414 (25 March 1998)     

Temperature dependence of the static dielectric constant of Rb2ZnBr4: Solitons in a modulated structure?

The static dielectric constant of Rb₂ZnBr₄ was measured as a function of temperature for a number of different single crystals. In a part of the samples a Curie-Weiss behaviour was observed at the lock-in transition from the incommensurate to the commensurate phase. Besides, in a few samples, a deviation of this behaviour was observed which can be ascribed to the appearance of solitons yielding a soliton density n_s proportional to $\text{(T?T}{}_{\mathrm{c}}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. At temperatures below T_c two new peaks are observed in the direction of the $\text{a}\text{-}\text{axis}$.     

Evidence for soft modes at q→≠0 ≠ 0 in the far-infrared spectrum of Rb2ZnBr4

The possibility to observe optically inactive and $\overrightarrow{q}\ne 0$ ≠ 0 soft modes in an indirect way by using far-infrared techniques is investigated. Using the fact that, due to anharmonicity, all modes of lattice vibrations are coupled with each other, the softening of one particular mode can be seen indirectly in the damping of other modes. By applying this idea to the modulated structure Rb₂ZnBr₄, the infrared inactive soft mode at the normal-incommensurable transition, the soft phason mode at the lock-in transition as well as a soft mode behaviour at an intermediate temperature have been observed.     

Ein anisotroper supraleitender Wärmeschalter

Summary An anisotropic superconducting thermal switch is described which depends upon the variation with angle of the magnetic field between two iron plates. This switch is intended for use in a cyclic adiabatic demagnetisation device employing an anisotropic paramagnetic salt in a rotating field.     

Pseudo-gap and possible Spin-Peierls transition in the vanadium oxide VOSb 2 O 4

We report on the magnetic susceptibility and electron spin resonance measurements on polycrystalline samples of the vanadium oxide VOSb₂O₄, a quasi-one-dimensional S = 1/2 Heisenberg system. The susceptibility vanishes at zero temperature, but there is no cusp at the onset of the susceptibility drop, and the ESR linewidth exhibits an increase characteristic of a phase transition at a much lower temperature. We show that this behaviour is consistent with the formation of a pseudo-gap in a spin-Peierls system in the adiabatic limit. Received 7 February 2001 and Received in final form 24 April 2001