arXiv subjects

Z. Kozioł

Publications and source records attributed to Z. Kozioł.

2 recordsLinked to original sources

arXiv1995

Magnetostriction of a Superconductor: -Results from the Critical-State Model

In many cases, the critical-state theory can be treated as a suffi ciently accurate approximation for the modelling of the magnetic properties of superconductors. In the present work, the magnetostrictive hysteresis is computed for a quite general case of the modified Kim-Anderson model. The results obtained reproduce many features of the giant magnetostriction (butterfly-shaped curves) reported in the literature for measurements made on single-crystal samples of the high-temperature superconductor $Bi_2Sr_2CaCu_2O_8$. It is shown that addition of a contribution to the magnetostriction in the superconducting state which is of similar origin as in the normal state, offers a broader phenomenological interpretation of the complex magnetostriction hysteresis found in such heavy-fermion compounds as $UPt_3$, $URu_2Si_2$ or $UBe_{13}$.

supr-con↗

arXiv1995

Nonlinear Flux Diffusion and ac Susceptibility of Superconductors - Exact Numerical Results

The ac response of a slab of material with electrodynamic characteristics $E\sim j^{κ+1}$, $κ\geq0$, is studied numerically. From the solutions of the nonlinear diffusion equation, the fundamental and higher-order components of the harmonic susceptibility are obtained. A large portion of the data for every $κ$ can be scaled by a single parameter, $ξ$ =$t^{1/(κ+2)}\cdot H_0^{κ/(κ+2)}/D$, where $t$ is the period of the ac field at the surface, $H_0$ is its amplitude and $D$ is the slab thickness. This is, however, only an approximate scaling property: The field penetration into a nonlinear medium is a more complex phenomenon than in the linear case. In particular, the susceptibility values are not uniquely defined by a set of only two parameters, such as $κ$ and $ξ$, while one parameter, i.e. $t^{1/2}$/D, is sufficient to describe the electrodynamic response of a linear medium.

supr-con↗