Suppression of spin-exciton state in hole overdoped iron-based superconductors

被引：17

作者：

Lee, C. H. ^{[1
]}

Kihou, K. ^{[1
]}

Park, J. T. ^{[2
]}

Horigane, K. ^{[3
]}

Fujita, K. ^{[3
]}

Wasser, F. ^{[4
]}

Qureshi, N. ^{[4
]}

Sidis, Y. ^{[5
]}

Akimitsu, J. ^{[3
]}

Braden, M. ^{[4
]}

机构：

[1] Natl Inst Adv Ind Sci & Technol, Tsukuba, Ibaraki 3058568, Japan

[2] Tech Univ Munich, Heinz Maier Leibnitz Zentrum MLZ, D-85748 Garching, Germany

[3] Aoyama Gakuin Univ, Sagamihara, Kanagawa 2525258, Japan

[4] Univ Cologne, Inst Phys 2, Zulpicher Str 77, D-50937 Cologne, Germany

[5] CEA, CNRS, LLB, F-91191 Gif Sur Yvette, France

来源：

SCIENTIFIC REPORTS | 2016年 / 6卷

基金：

日本学术振兴会;

关键词：

EXCITATIONS;

D O I：

10.1038/srep23424

中图分类号：

O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];

学科分类号：

07 ; 0710 ; 09 ;

摘要：

The mechanism of Cooper pair formation in iron-based superconductors remains a controversial topic. The main question is whether spin or orbital fluctuations are responsible for the pairing mechanism. To solve this problem, a crucial clue can be obtained by examining the remarkable enhancement of magnetic neutron scattering signals appearing in a superconducting phase. The enhancement is called spin resonance for a spin fluctuation model, in which their energy is restricted below twice the superconducting gap value (2 Delta(s)), whereas larger energies are possible in other models such as an orbital fluctuation model. Here we report the doping dependence of low-energy magnetic excitation spectra in Ba1-xKxFe2As2 for 0.5 < x < 0.84 studied by inelastic neutron scattering. We find that the behavior of the spin resonance dramatically changes from optimum to overdoped regions. Strong resonance peaks are observed clearly below 2 Delta(s) in the optimum doping region, while they are absent in the overdoped region. Instead, there is a transfer of spectral weight from energies below 2 Delta(s) to higher energies, peaking at values of 3 Delta(s) for x = 0.84. These results suggest a reduced impact of magnetism on Cooper pair formation in the overdoped region.

引用

页数：7

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