Avoided Quantum Criticality and Magnetoelastic Coupling in BaFe2-xNixAs2

Xingye Lu, H. Gretarsson, Rui Zhang, Xuerong Liu, Huiqian Luo, Wei Tian, Mark Laver, Z. Yamani, Young-June Kim, A. H. Nevidomskyy, Qimiao Si, Pengcheng Dai

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We study the structural and magnetic orders in electron-doped BaFe2-xNixAs2 by high-resolution synchrotron x-ray and neutron scatterings. Upon Ni doping x, the nearly simultaneous tetragonal-to-orthorhombic structural (Ts) and antiferromagnetic (NT) phase transitions in BaFe2As2 are gradually suppressed and separated, resulting in sNT>T with increasing x, as was previously observed. However, the temperature separation between sT and NT decreases with increasing x for x≥0.065, tending toward a quantum bicritical point near optimal superconductivity at x≈0.1. The zero-temperature transition is preempted by the formation of a secondary incommensurate magnetic phase in the region 0.088≲x≲0.104, resulting in a finite value of NTcT+10 K above the superconducting dome around x≈0.1. Our results imply an avoided quantum critical point, which is expected to strongly influence the properties of both the normal and superconducting states.

Original languageEnglish
JournalPhysical Review Letters
Issue number25
Pages (from-to)257001
Publication statusPublished - 2013

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© 2013 American Physical Society

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