Susceptibility, magnetisation and critical behaviour of a magnetic superconductor:Y₉Co₇

Abstract

We present detailed measurements of the AC susceptibility and magnetisation as functions of temperature and magnetic field for the magnetic superconductor Y gCo7 and compare them with the mean-field theories and the self-consistent renormalisation theory of spin fluctuations.We have also determined the critical exponents and y from the asymptotic relations for the critical behaviour of the magnetisation and susceptibility.We have found further evidence that the weak itinerant ferromagnetism of the intermetallic compound Y9Co, is of double character with two groups of CO magnetic behaviour.Comparing the magnetisation data wsith the theory we have extended the zero-field magnetisation curve up to 0 K, finding further evidence of the coexistence of ferromagnetism and superconductivity.