4 that in this phase the magnetic susceptibility shows a Curie component but the value of the magnetic moment of the localized electrons is enhanced by the presence of the itinerant electrons. Indeed the Hund’s coupling fer- romagnetic correlation between the on-site spin in the different orbitals induces a local moment in the itiner- ant bands. The value of the total effective moment is thus larger than the simple one of the localized compo- nent and grows with J . Indeed this can be shown by very simple arguments using the effective model for the OSMP introduced in [17]. In this simplified picture of the OSMP one can show that the local magnetic susceptibility has the form where χ$_{it}$ is the local susceptibility of the itinerant part (still Pauli-like) and M$_{it}$ ( H ) is the magnetic moment induced by a local field H in the itinerant component. A detailed comparison between experimental results for the magnetic response and a more realistic calcula- tion based on the combination of many-body approaches and realistic bandstructure is the natural extension of the present analysis. It is worth noting that through a similar comparison one could obtain an accurate es- timate for an otherwise elusive quantity, the Hund’s interaction J . χ$_{loc}$ = χ$_{it}$ + ( M$_{it}$ [ J/ 2] + 1 $_{2}$) 2 T , (1) In this paper we have discussed the possibility of an orbital-selective Mott transition in a five-band model which is a backbone description of the electronic struc- ture of the pnictides. We found a realization of the tran- sition proposed in Ref. [6], where the OSMT is deter- mined by the lifting of the orbital degeneracy due to a (reasonably small) crystal field splitting. The relevance of band-selective properties in multiband superconduc- tivity has been indeed proposed in the context of the cuprates[18] and pnictides[19] Acknowledgements We acknowledge financial support of MIUR PRIN 2007 Prot. 2007FW3MJX003 References 1. Y. Kamihara et al. , J. Am Chem. Soc. 128 , 10012 ( 2006); ibid. 130 , 3296 (2008) 2. A, Comanac, L. de’ Medici, M. Capone, and A. J. Millis, Nat. Phys. 4 , 287 (2008) 3. Q. Si, E. Abrahams, J. Dai, J. X. Zhu, arXiv:0901.4112v1 4. Y. Sekiba, T. Sato, K. Nakayama, K. Terashima, P. Richard, J. H. Bowen, H. Ding, Y.-M. Xu, L. J. Li, G. H. Cao, Z.-A. Xu, T. Takahashi, arXiv:0812.4111; H. Ding, K. Nakayama, P. Richard, S. Souma, T. Sato, T. Takahashi, M. Neupane, Y.-M. Xu, Z.-H. Pan, A.V. Federov, Z. Wang, X. Dai, Z. Fang, G.F. Chen, J.L. Luo, N.L. Wang, arXiv:0812.0534 5. T. Nomura, S. W. Kim, Y. Kamihara, M. Hirano, P. V. Sushko, K. Kato, M. Takata, A. L. Shluger, H. Hosono, Supercond. Sci. Technol. 21 , 125028 (2008) 6. L. de’ Medici, S.R.Hassan, M. Capone, X. Dai, (2008). Phys. Rev. Lett. 102 , 126401 (2009) 7. P. Lu, Phys. Rev. B 49 , 5687 (1994) 8. M.J. Rozenberg, Phys. Rev. B 55 , R4855 (1997) 9. O. Gunnarsson, E. Koch, R. Martin, Phys. Rev. B 54 , R11026 (1996) 10. O. Gunnarsson, E. Koch, R. Martin, Phys. Rev. B 56 , 1146 (1997) 11. E. Koch, O. Gunnarsson, R.M. Martin, Phys. Rev. B 60 , 15714 (1999) 12. S. Florens, A. Georges, G. Kotliar, O. Parcollet, Phys. Rev. B 66 , 205102 (2002) 13. K. Haule, J. Shim, G. Kotliar, Phys. Rev. Lett. 100 , 226402 (2008) 14. K. Haule, G. Kotliar, arXiv:0805.0722 15. A. Georges, G. Kotliar, W. Krauth, M.J. Rozenberg, Rev. Mod. Phys. 68 , 13 (1996) 16. T.Pruschke, R. Bulla, Eur. Phys. J. B 44 , 217 (2005) 18. N. Kristoffel, P. Rubin and T. ¨ Ord, J. Phys.: Conf. Ser. 108 012034; F. V. Kusmartsev and M. Saarela, Supercond. Sci. Technol. 22 , 014008 (2009) 17. S. Biermann, L. de’ Medici, A. Georges, Phys. Rev. Lett. 95 , 206401 (2005) 19. R. Caivano et. al. , Supercond. Sci. Technol. 22 , 014004 (2009)