Reentrant superconductivity in a composite formed by YBa$_2$Cu$_3$O$ _{7-δ}$ and Ammonium Terbium Oxalate

Abstract: We present a study of reentrant behavior in a composite formed by a Hight-T$ _{c} $ superconductor, YBa$_2$Cu$_3$O$ _{7-\delta}$ and Ammonium Terbium Oxalate, Tb(H$_2$O)(C$ _2$O$_4$)$_2$ $\cdot $NH$_4$. The composite has a transition temperature about 92 K, and it presents a reentrant behaviour resulting of the coexistence between superconductivity and magnetism. According to this study the values and shape of the critical magnetic fields were dramatically reduced in a similar form as in other known reentrant superconductors.