Nuclear ferromagnetism and superconductivity at negative nuclear temperatures

Quantitative theory of the effect of nuclear ferromagnetism on the supercon ductivity of metals is proposed taking into account the electron-nuclear sp in-spin interactions. At negative nuclear temperatures, when the nuclear ma gnetization is in opposition to an external magnetic field, nuclear ferroma gnetism is favorable to superconductivity rather than suppressing it. The c ritical magnetic field in Be and TiH2.07 hydrate metals may exceed the crit ical field of a nonmagnetic superconductor by an order of magnitude. (C) 20 01 MAIK "Nauka/Interperiodica".