| 日時: |
2013-08-02 16:00 - 17:30 |
| 場所: |
MLF第一会議室（東海）/4号館2階輪講室1 |
| 会議名: |
物構研談話会（13-09）Spin Excitations in Ovserdoped Ba(Fe1-xCox)2As2 |
| 連絡先: |
中尾 裕則 6025 |
| 講演者: |
Andrew Christianson 氏 (オークリッジ国立研究所) |
| アブストラクト: |
The relationship between spin excitations and unconventional superconductivity has been and continues to be the subject of considerable experimental and theoretical scrutiny. While the underdoped and optimally doped regions of the phase diagrams of unconventional superconductors have been extensively studied there have been few studies of the spin excitations in the overdoped region. Here we report an inelastic neutron scattering study of an overdoped sample of the unconventional superconductor Ba(Fe1-xCox)2As2 with x=0.11 and Tc = 12 K. At energies below 40 meV the spin excitations are much broader and weaker when compared to samples close to optimal doping. Despite the weakness of the spin excitations a broad spin resonance is still observed at an energy of ~6.5 meV at the wave vector (0.5 0.5 0). This corresponds to a value of 6.5 KBTc which is substantially larger than the value of 4.5 KBTc found for many Fe-based superconductors. Above 40 meV well defined spin excitations are observed which extend to energies at least as high 300 meV. This energy scale equals or surpasses the energy scale of the spin excitations previously observed in the parent compound BaFe2As2. This work demonstrates that strong spin excitations extend well into the overdoped region of the phase diagram and are available as a source of pairing within a spin fluctuation mediated picture. |
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