Superconductivity and ferromagnetism are antagonistic types of ordering, and their mutual effects give rise to several interesting phenomena which have recently been studied in rare earth compounds. A theoretical analysis shows that while a ferromagnetic superconductor is a type II superconductor near the superconducting transition point $T_\mathrm{c1}$, it becomes a type I superconductor near the ferromagnetic transition point $T_\mathrm{M}$. A new theory derived for the case $T_\mathrm{M}\ll T_\mathrm{c1}$ predicts the formation of a transverse domain-like magnetic structure near $T_\mathrm{M}$. In clean superconductors the electron spectrum is gapless. A change in the behavior from type II to type I upon cooling to TM has been observed experimentally in ErRh$_4$B$_4$. Experimental data on ErRh$_4$B$_4$, HoMo$_6$Se$_8$ and HoMo$_6$Se$_8$ prove the existence of superconductivity and a magnetic ordering below $T_\mathrm{M}$.

PT Journal Article
TI Magnetic superconductors
AU Buzdin A I
FAU Buzdin AI
AU Bulaevskii L N
FAU Bulaevskii LN
AU Kulich M L
FAU Kulich ML
AU Panyukov S V
FAU Panyukov SV
DP 10 Dec, 1984
TA Phys. Usp.
VI 27
IP 12
PG 927-953
RX 10.1070/PU1984v027n12ABEH004085
URL https://ufn.ru/en/articles/1984/12/b/
SO Phys. Usp. 1984 Dec 10;27(12):927-953