Research for Superconducting Pairing Symmetry in Unconventional Superconductors by Geometry Effects

利用几何效应研究非常规超导体中的超导配对对称性

• 批准号: 18540329
• 负责人: TENYA Kenichi
• 金额: $ 2.37万
• 依托单位: Shinshu University (2007)Hokkaido University (2006)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18540329/
• 关键词: spin-triplet superconductivity; unconventional superconductivity; Little-Parks oscillation; magnetization measurements; Sr_2RuO_4; Little-Parks振動; 磁化機構

From several experimental results, the layered ruthenate Sr_2RuO_4 is evidenced to be a spin-triplet superconductor with the degenerate chiral d-vector. In the spin-triplet superconductors with chiral d-vectot dynamics on the two superconducting domains with opposite chiralities is expected to be experimentally observed. In order to investigate the chiral superconducting characteristics as well as the vortex-pinning properties, the measurements of Little-Parks oscillation and static magnetization on the single crystalline samples Sr_2RuO_4 have been performed in the field direction parallel to the [001) axis.For the Little-Parks oscillation measurement, tiny single crystalline samples of Sr_2RuO_4 with small holes were prepared by using FIB. We succeed in observing the phenomena that the resistivity of the samples periodically oscillates with field, and we are checking whether this oscillation is really intrinsic to the superconductivity or not.Anomalous pinning features are found at weak fields in the magnetization curves in the superconducting mixed state: Tiny flux-jumps successively appear around zero-field at temperature up to at least 0.2 K. At higher temperatures, a small peak of the hysteretic magnetization is observed below 0.1 kOe, which is so-called second magnetization peak (SMP). The magnitude of the hysteretic magnetization is strongly dependent on (independent of) the field-gradient in the field region below (above) the field HSMP where the SMP appears. These phenomena can be explained by assuming that the superconducting &domains easily move under the field-gradient or super current flow, leading to the reduction of the effective pinning-force at the domain boundaries. Another possible origin of the anomalous magnetization features around HSMP is the topological transition in the vortex-state from Bragg-glass to vortex-glass, occasionally observed in "super-clean" type II superconductors.

从几个实验结果证明，层状Ruthenate Sr2RuO4是具有简并手征d矢量的自旋三重态超导体。在具有手性d向量动力学的自旋三重态超导体中，有望在具有相反手性的两个超导区上观察到。为了研究Sr2RuO4的手征超导特性和涡钉扎特性，在平行于[001]轴的磁场方向上测量了Sr2RuO4单晶样品的Little-Parks振荡和静态磁化强度。我们成功地观察到了样品的电阻率随场的周期性振荡的现象，并验证了这种振荡是否是超导本征的。在超导混合态的磁化曲线的弱场处发现了异常的钉扎特征：在至少0.2K的温度下，在零场附近连续出现微小的磁通跳跃。在更高的温度下，在0.1KoE以下观察到磁滞磁化强度的一个小峰值，即所谓的第二磁化峰(SMP)。磁滞磁化强度的大小强烈地依赖于(独立于)出现SMP的场HSMP下方(上方)场区中的场梯度。这些现象可以通过假设超导磁区在磁场梯度或超流作用下容易移动，导致磁区边界的有效钉扎力减小来解释。超高纯净第二类超导体中的反常磁化特征的另一个可能来源是涡旋态从布拉格玻璃到涡旋玻璃的拓扑转变。

项目成果

Polarized neutron scattering study on antiferromagnetic states in CeRh_0.6Co_o.4In_5

CeRh_0.6Co_o.4In_5反铁磁态的偏振中子散射研究

• 发表时间: 2008
• 期刊: Physica B 403
• 作者: M. Yokoyama;H. Amitsuka;K. Tenya;I. Kawasaki;M. Yokoyama
• 通讯作者: M. Yokoyama

Low-energy magnetic fluctuations in U(Ru_1-xRh_x)_2Si_2(x〓0.02)

U(Ru_1-xRh_x)_2Si_2(x〓0.02)中的低能磁涨落

• 发表时间: 2007
• 期刊: J. Magn. Magn. Matter 310
• 作者: M. Yokoyama;H. Amitsuka;K. Tenya;I. Kawasaki;M. Yokoyama;H. Amitsuka;I. Kawasaki;H. Amitsuka;H. Amitsuka;A. Morishita;M. Yokoyama;K. Matsuda;H. Amitsuka;A. Morishita;M. Yokoyama
• 通讯作者: M. Yokoyama

Anomalous Pinning Behaviors in Sr_2RuO_4

Sr_2RuO_4 中的异常钉扎行为

• 发表时间: 2007
• 作者: M. Yokoyama;H. Amitsuka;K. Tenya;I. Kawasaki;M. Yokoyama;H. Amitsuka;I. Kawasaki;H. Amitsuka;H. Amitsuka;A. Morishita;M. Yokoyama;K. Matsuda;H. Amitsuka;A. Morishita;M. Yokoyama;K. Matsuda;M. Yokoyama;K. Tenya;M. Yokoyama;M. Yokoyama;K.Tenya.;M.Yokoyama;横山 淳;山塙 亮太;延兼 啓純;森下 明;川崎 郁斗;K. Tenya
• 通讯作者: K. Tenya

Anomalous pinning behavior in Sr2RuO4

Sr2RuO4 中的异常钉扎行为

• 发表时间: 2008
• 期刊: Physica B-Condensed Matter 403(5-9)
• 作者: K. Tenya;R. Yamahana;M. Yokoyama;H. Amitsuka;K. Deguchi;and Y. Maeno
• 通讯作者: and Y. Maeno

Single-site effects of Pr and U ions doped in RRu_2Si_2 (R = Th, Y and La)

RRu_2Si_2 (R = Th、Y 和 La) 中掺杂 Pr 和 U 离子的单中心效应

• 发表时间: 2007
• 期刊: J. Magn. Magn. Matter 310
• 作者: M. Yokoyama;H. Amitsuka;K. Tenya;I. Kawasaki;M. Yokoyama;H. Amitsuka;I. Kawasaki;H. Amitsuka;H. Amitsuka;A. Morishita;M. Yokoyama;K. Matsuda;H. Amitsuka;A. Morishita
• 通讯作者: A. Morishita