The electronic phase diagram of the LaO(1-x)F(x)FeAs superconductor.
NATURE MATERIALS 2009;
8:305-309. [PMID:
19234445 DOI:
10.1038/nmat2397]
[Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 01/20/2009] [Indexed: 05/27/2023]
Abstract
The competition of magnetic order and superconductivity is a key element in the physics of all unconventional superconductors, for example in high-transition-temperature cuprates, heavy fermions and organic superconductors. Here superconductivity is often found close to a quantum critical point where long-range antiferromagnetic order is gradually suppressed as a function of a control parameter, for example charge-carrier doping or pressure. It is believed that dynamic spin fluctuations associated with this quantum critical behaviour are crucial for the mechanism of superconductivity. Recently, high-temperature superconductivity has been discovered in iron pnictides, providing a new class of unconventional superconductors. Similar to other unconventional superconductors, the parent compounds of the pnictides show a magnetic ground state and superconductivity is induced on charge-carrier doping. In this Letter the structural and electronic phase diagram is investigated by means of X-ray scattering, muon spin relaxation and Mössbauer spectroscopy on the series LaO(1-x)F(x)FeAs. We find a discontinuous first-order-like change of the Néel temperature, the superconducting transition temperature and the respective order parameters. Our results strongly question the relevance of quantum critical behaviour in iron pnictides and prove a strong coupling of the structural orthorhombic distortion and the magnetic order both disappearing at the phase boundary to the superconducting state.
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