The deliberate insertion of magnetic Mn dopants in the Fe sites of the optimally doped SmFeAsO0.88F0.12 iron-based superconductor can modify in a controlled way its electronic properties. The resulting phase diagram was investigated across a wide range of manganese contents (x) by means of muon-spin spectroscopy (mu SR), both in zero and in transverse fields, to probe the magnetic and the superconducting order, respectively. The pure superconducting phase (at x < 0.03) is replaced by a crossover region at intermediate Mn values (0.03 <= x < 0.08), where superconductivity coexists with static magnetic order. After completely suppressing superconductivity for x = 0.08, a further increase in Mn content reinforces the natural tendency towards antiferromagnetic correlations among the magnetic Mn ions. The sharp drop of T-c and the induced magnetic order in the presence of magnetic disorder/dopants, such as Mn, are both consistent with a recent theoretical model of unconventional superconductors (M. N. Gastiasoro et al., Phys. Rev. Lett. 117, 257002 (2016)), which includes correlation-enhanced RKKY couplings between the impurity moments.

Role of magnetic dopants in the phase diagram of Sm 1111 pnictides: The case of Mn

SANNA, SAMUELE;MORONI, MATTEO;CARRETTA, PIETRO;
2016

Abstract

The deliberate insertion of magnetic Mn dopants in the Fe sites of the optimally doped SmFeAsO0.88F0.12 iron-based superconductor can modify in a controlled way its electronic properties. The resulting phase diagram was investigated across a wide range of manganese contents (x) by means of muon-spin spectroscopy (mu SR), both in zero and in transverse fields, to probe the magnetic and the superconducting order, respectively. The pure superconducting phase (at x < 0.03) is replaced by a crossover region at intermediate Mn values (0.03 <= x < 0.08), where superconductivity coexists with static magnetic order. After completely suppressing superconductivity for x = 0.08, a further increase in Mn content reinforces the natural tendency towards antiferromagnetic correlations among the magnetic Mn ions. The sharp drop of T-c and the induced magnetic order in the presence of magnetic disorder/dopants, such as Mn, are both consistent with a recent theoretical model of unconventional superconductors (M. N. Gastiasoro et al., Phys. Rev. Lett. 117, 257002 (2016)), which includes correlation-enhanced RKKY couplings between the impurity moments.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11571/1179389
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