Suprastriction in Superconductors

Abstract

Mit Hilfe der mikromagnetischen Grundgleichungen der Supraleitung werden die unterhalb der Sprungtemperatur auftretenden Deformationen eines Supraleiters berechnet. Es wird gezeigt, dal3 sich in Analogie zu ferromagnetischen Stoffen die Deformationen eines Supraleiters als spontane und erzwungene Suprastriktion sowie als Formeffekt deuten lassen. Die theoretischen Ergebnisse werden mit neueren Experimenten verglichen. Introductory RemarksThe difference in volume between the normal and the superconducting state was first observed by Lasarev and Sudovstov [l]. The temperature dependence of this so-called AV-effect was investigated by White In zero magnetic field no volume change is observed a t To whereas the expansion coefficient ( l / V ) (dV/dT) shows a discontinuity in agreement with the effects expected for a second order phase transition (compare Fig. 1). I n the presence of a magnetic field the superconducting transition is accompanied by a AV-effect, which according to Shoenberg [7] is given by

The Flux‐Line Lattice in Type‐II Superconductors

“…A very general formulation of the interaction of PTJs with the tensorial stress field caused by crystal lattice defects is given by Seeger and Kronmuller [GO, 671. Parts of this interaction have been interpreted i) as scalar "volume effect" (associated with the volume change in the FL cores) and tensorial ('suprastriction" [68] (analogous to the magnetostrictive interaction of crystal-latticedefects withBloch walls in ferromagnets), ii) as interaction with quasi-dislocations [69] (which formally describe the internal stress caused by a FL), and iii) as paraelastic interaction [70]. An elegant, less general formulation [71] was applied t o the interaction of a FL with a crystal dislocation parallel to it [71 to 731.…”

The vortex lattice in superconductors

“…Finite k may be accounted for by modifying the current±voltage law, using E E v JY B l 0 k 2 qjaqt; here, the first term is generated by moving vortices, and the second term describes the Meissner surface currents [5]. After computation of the magnetic field and current density inside the superconductor, one can calculate also the ªsuprastrictionº of the atomic lattice, as described first by Kronmu Èller [42]. …”

The Elementary Interaction between a Crystal Dislocation and the Flux Line Lattice of a Type II Superconductor

“…As has been shown previously [21], the remaining magnetic part AG$ can be written in the following useful way: have to be added to the equilibrium condition (3.5). I n order to determine all six components of the strain tensor, the so-called…”

“…As has been shown previously [21], the remaining magnetic part AG$ can be written in the following useful way:…”