Specific heat of iron-based high-Tc superconductors Li Ding (No. 061019019),1 J. K. Dong,1 T. Wu,2 R. H. Liu,2 G Wu2, X. H. Chen,2 and S. Y. Li1 1Department of Physics and Laboratory of Advanced Materials,, Fudan University, Shanghai 200433, China 2Hefei National Laboratory for Physical Science at Microscale and Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China Summary A specific heat jump was observed at 130K for the x = 0 sample, corresponding to the structural or SDW transition. However, it disappears in x = 0.05 sample, indicating the suppression of the SDW order and structural distortion by electron doping in this system A clear specific heat anomaly can be seen near Tc for superconducting SmO1−xFxFeAs samples, while it has been absent in LaO1−xFxFeAs. This result suggests higher superfluid density in SmO1−xFxFeAs. A clear peak of C/T can be seen at Tc = 36K for Ba0.5K0.5Fe2As2. No obvious anomaly is found below Tc = 18K for Ca0.5Na0.5Fe2As2 The electronic specific heat coefficients of these compounds were obtained. Main References [1] X. H. Chen, T. Wu, G. Wu, R. H. Liu, H. Chen, D. F. Fang, Nature 453,761-762 (2008). [2] R. H. Liu, G. Wu, T. Wu, D. F. Fang, H. Chen, S. Y. Li, K. Liu, Y. L. Xie, X. F. Wang, R. L. Yang, L. Ding, C. He, D. L. Feng, X. H. Chen, Phys. Rev. B 101, 087001 (2008). [3] J. Dong, H. J. Zhang, G. Xu, Z. Li, G. Li, W. Z. Hu, D. Wu, G. F. Chen, X. Dai, J. L. Luo, Z. Fang, N. L. Wang, Europhysics Letters 83, 27006 (2008). [4] Rotter M, Tegel M, Johrendt D, Schellenberg I, Hermes W and Pottgen R Phys. Rev. B 78 020503 (2008). Published Papers: L. Ding, et al, Phys. Rev. B 77, 180510(R) (2008) J. K. Dong, L. Ding, et al, New Journal of Physics 10 123031 (2008)