ID 31864
本文ファイル
別タイトル
Sr_2RuO_4の超伝導および常伝導状態の異方的特性
著者
吉田 宏二
NDC
物理学
抄録(英)
We have recently discovered superconductivity of Sr2RuO4 with Tc ≈ 1 K. This compound is the only layered perovskite superconductor without copper that is known so far: the same crystal structure as a high-Tc superconducting copper oxide. In this study, we have investigated the superconducting and normal-state properties of Sr2RuO4 by measuring the electrical resistivity, magnetic susceptibility and specific heat using single crystals.

In the normal state we found the T2 dependence of the resistivity below 25 K, the enhanced paramagnetic spin susceptibility, and the enhanced Sommerfeld coefficient of the specific heat. These three results can consistently be described as a highly-anisotropic Fermi-liquid behavior of the normal state of Sr2RuO4. In addition, concerning the peculiar temperature dependence of the resistivity along the c axis, we present a systematic interpretation based on competition between the life time of the quasiparticles governed by a number of scattering processes and the time for the quasiparticles to travel the interlayer distance d.

From the upper critical fields Hc2, we will show that the superconducting state of Sr2RuO4 is also highly anisotropic with the ratio of the coherence lengths Γs = ξab(0)/ξc(0) = 26 evaluated for zero temperature. Furthermore, we found peculiar anisotropic flux-pinning behavior: a second dissipation peak in the ac susceptibility prominently appears only when the direction of the flux lines, as well as of their induced motions, is parallel to the ab planes. The peak effect in Sr2RuO4 is attributed to the synchronization of the flux lines to the pinning centers as the flux-line lattice softens with increasing magnetic field and temperature.

In this study we clarify that Sr2RuO4 serves as an ideal reference material for investigation of the limits of applicability of the Fermi liquid theory to other highly correlated layered compounds, including high-Tc cuprates. In addition, the comparison with these physical properties of Sr2RuO4 and those of high-Tc superconductors are very important to clarify the mechanism of the high Tc, which still remains unclear at present.
目次
Abstract / p1
Contents / p2
1.Introduction / p3
2.Experimental / p6
 2.1 Sample preparation / p6
 2.2 Measurements / p6
3.Normal-State Properties / p7
 3.1 Experimental results / p7
 3.2 Highly anisotropic Fermi liquid state / p9
 3.3 Anomalous temperature dependence of resistivity along the c axis / p10
4.Superconducting Properties / p15
 4.1 Anisotropic superconducting state / p15
 4.2 Peculiar flux pinning in the mixed state / p17
5.Conclusions / p23
Acknowledgments / p25
References / p26
SelfDOI
言語
英語
NII資源タイプ
学位論文
広大資料タイプ
学位論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
ETD
権利情報
Copyright(c) by Author
関連情報(references)
Anisotropic superconductivity of Sr2RuO4, K. Yoshida, Y. Maeno, S. Nishizaki and T. Fujita, to be published in Physica C.
関連情報URL(references)
http://dx.doi.org/10.1016/0921-4534(95)00728-8
学位記番号
甲第1435号
授与大学
広島大学(Hiroshima University)
学位名
博士(理学)
学位名の英名
Physical Science
学位の種類の英名
doctoral
学位授与年月日
1996-03-26
部局名
理学研究科