1. Specific heat jump near the onset of co-existence with antiferromagnetsism

2. In a BCS superconductor (s-wave)  C/T c = 1.43  Now suppose superconductivity emerges from a pre-existing SDW order:

3. Do simple mean-field: And then include gaussian fluctuations  C/T c has a maximum at the onset of co-existence and drops on both sides of this critical doping

4. Data: C. Meingast et al Theory: Vorontsov et al X =0.95 Co-existence state Mean-field

5. BaFe2 (As 1-x P x ) 2 Data: A. Carrington et al Theory: D. Kuzmanovski et al Normal state Gaussian fluct.