摘要
Electron pairing along with phase coherence generates superconductivity below the critical temperature(T_(c)).In underdoped highT_ccuprates,these two quantum phenomena may occur at separate temperatures,which was lately confirmed in the quasi-twodimensional(quasi-2D)iron chalcogenide superconductors.Here,we report a systematic investigation on the pre-pairing behavior in a triclinic iron pnictide superconductor(Ca_(0.85)La_(0.15))_(10)(Pt_(3)As_(8))(Fe_(2)As_(2))_(5)with T_(c)≈30 K,where the superconductivity is quasi-2D manifested by the Berezinskii-Kosterlitz-Thouless behaviors.Inelastic neutron scattering experiments unambiguously reveal a spin resonance peak around E_(R)=13 me V in the superconducting state,but its intensity continuously decreases when warming up across T_(c),accompanied with an anomaly around T^(*)≈45 K in spin correlations,and a suppression by an in-plane magnetic field persisting to the same temperature.Below T^(*),a significant Nernst signal and a reduction of density of states at the Fermi level are also observed.These results suggest that the precursor of spin resonance is highly related to the preformed Cooper pairs driven by phase fluctuations,much like the pseudogap case in cuprates.
基金
supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406100,2018YFA0704200
2020YFA0406000)
the National Natural Science Foundation of China(Grant Nos.11822411,11874057,and 11961160699)
the Strategic Priority Research Program(B)of the CAS(Grant Nos.XDB25000000
XDB33000000)
the K.C.Wong Education Foundation(Grant No.GJTD-2020-01)
the support from the Youth Innovation Promotion Association of CAS(Grant No.Y202001)
the support from the Postdoctoral Innovative Talent program(Grant No.BX2021018)
the China Postdoctoral Science Foundation(Grant No.2021M700250)。
