Effect of the sample geometry on the second magnetization peak in single crystalline Ba${}_{0.63}$K${}_{0.37}$BiO${}_3$ thick film

Magnetization hysteresis loop $M(H)$ measurements performed on a single crystalline Ba${}_{0.63}$K${}_{0.37}$BiO${}_3$ superconducting thick film reveal pronounced sample geometry dependence of the “second magnetization peak” (SMP), i.e. a maximum in the width of $M(H)$ occurring at the field $H_{\mathrm{S}\mathrm{M}\mathrm{P}}(T)$. In particular, it is found that the SMP vanishes decreasing the film dimension. We argue that the observed sample geometry dependence of the SMP cannot be accounted for by models which assume a vortex pinning enhancement as the origin of the SMP. Our results can be understood considering the thermomagnetic instability effect and/or non-uniform current distribution at $H<H_{\mathrm{S}\mathrm{M}\mathrm{P}}$ in large enough samples.