Anisotropic Behavior of Knight Shift in Superconducting State of NaxCoO2·yH2O
Anisotropic Behavior of Knight Shift in Superconducting State of NaxCoO2·yH2O
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DOI：
10.1143/jpsj.75.013708
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发表时间：
2005-11
影响因子：
1.7
通讯作者：
Y. Ihara;K. Ishida;H. Takeya;C. Michioka;M. Kato;Y. Itoh;K. Yoshimura;K. Takada;T. Sasaki;H. Sakurai;E. Takayama-Muromachi
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文献类型：
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作者：
Y. Ihara;K. Ishida;H. Takeya;C. Michioka;M. Kato;Y. Itoh;K. Yoshimura;K. Takada;T. Sasaki;H. Sakurai;E. Takayama-Muromachi
测量了取向的NaxCoO2·yH2O粉末样品的Co奈特位移，其超导温度为4.6K。在正常态和超导(Sc)态下，测量了平行(Kc)和垂直于c轴(沿a b平面K a b)的奈特位移分量。K a b和K c随温度的变化与体磁化率成比例关系，这表明由Knight位移得到的微观磁化率与Co-3d自旋有关.在Sc态，Knight位移表现出各向异性的温度依赖关系：Ka b减小到5K以下，而Kc不在实验精度范围内减小。这一结果提出了在NaxCoO2·yH2O中实现具有沿c轴方向的对的自旋分量的自旋三重态超导的可能性。
The Co Knight shift was measured in an aligned powder sample of Na x CoO 2 · y H 2 O, which shows superconductivity at T c ∼4.6 K. The Knight-shift components parallel ( K c ) and perpendicular to the c -axis (along the a b plane K a b ) were measured in both the normal and superconducting (SC) states. The temperature dependences of K a b and K c are scaled with the bulk susceptibility, which shows that the microscopic susceptibility deduced from the Knight shift is related to Co-3 d spins. In the SC state, the Knight shift shows an anisotropic temperature dependence: K a b decreases below 5 K, whereas K c does not decrease within experimental accuracy. This result raises the possibility that spin-triplet superconductivity with the spin component of the pairs directed along the c -axis is realized in Na x CoO 2 · y H 2 O.