Magnetic field effects on $T_c$ and the pseudogap onset temperature in cuprate superconductors

摘要

We study the sensitivity of $T_c$ and the pseudogap onset temperature, $T^*$, to low fields, $H$, for cuprate superconductors, using a BCS-basedapproach extended to arbitrary coupling. We find that $T^*$ and $T_c$, whichare of the same superconducting origin, have very different $H$ dependences.The small coherence length makes $T^*$ rather insensitive to the field.However, the presence of the pseudogap at $T_c$ makes $T_c$ more sensitive to$H$. Our results for the coherence length $\xi$ fit well with existingexperiments. We predict that very near the insulator $\xi$ will rapidlyincrease.