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セガワ コウジ
SEGAWA KOJI
瀬川 耕司 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 言語種別 | 英語 |
| 発行・発表の年月 | 2008/01 |
| 形態種別 | 研究論文 |
| 標題 | Quantum spin excitations through the metal-to-insulator crossover in YBa(2)Cu(3)O(6+y) |
| 執筆形態 | その他 |
| 掲載誌名 | PHYSICAL REVIEW B |
| 出版社・発行元 | AMER PHYSICAL SOC |
| 巻・号・頁 | 77(1) |
| 著者・共著者 | Shiliang Li,Zahra Yamani,Hye Jung Kang,Kouji Segawa,Yoichi Ando,Xin Yao,H. A. Mook,Pengcheng Dai |
| 概要 | We use inelastic neutron scattering to study the temperature dependence of the spin excitations of a detwinned superconducting YBa(2)Cu(3)O(6.45) (T(c)=48 K). In contrast to earlier work on YBa(2)Cu(3)O(6.5) (T(c)=58 K), where the prominent features in the magnetic spectra consist of a sharp collective magnetic excitation termed "resonance" and a large (h omega approximate to 15 meV) superconducting spin gap, we find that the spin excitations in YBa(2)Cu(3)O(6.45) are gapless and have a much broader resonance. Our detailed mapping of magnetic scattering along the a(*)/b(*)-axis directions at different energies reveals that spin excitations are unisotropic and consistent with the "hourglasslike" dispersion along the a(*)-axis direction near the resonance, but they are isotropic at lower energies. Since a fundamental change in the low-temperature normal state of YBa(2)Cu(3)O(6+y) when superconductivity is suppressed takes place at y similar to 0.5 with a metal-to-insulator crossover (MIC), where the ground state transforms from a metallic to an insulatinglike phase, our results suggest a clear connection between the large change in spin excitations and the MIC. The resonance therefore is a fundamental feature of metallic ground state superconductors and a consequence of high-T(c) superconductivity. |
| DOI | 10.1103/PhysRevB.77.014523 |
| ISSN | 1098-0121 |
| PermalinkURL | https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=38549107010&origin=inward |