Nonvolatile Magneto-Thermal Switching in MgB2

Ongoing research explores thermal switching materials to control heat flow. Specifically, there has been interest in magneto-thermal switching (MTS) materials based on superconductors, which only exhibited switching behavior when a magnetic field was applied. However, a recent report highlighted nonvolatile MTS in commercial Sn-Pb solders that was attributed to magnetic flux trapping. In this study, we focused on flux trapping in a type-II superconductor, MgB2. Magnetization and thermal conductivity measurements under magnetic fields were conducted on polycrystalline MgB2. We confirmed that magnetic flux was indeed trapped in MgB2 even after demagnetization. Additionally, we observed nonvolatile MTS in MgB2 as well as Sn-Pb solders. These results suggest that the nonvolatile MTS may be a widespread characteristic of superconducting materials with flux trapping.