Observation of 105 Pd NMR and NQR signals in the heavy-fermion superconductor UPd 2 Al 3
Observation of 105 Pd NMR and NQR signals in the heavy-fermion superconductor UPd 2 Al 3
复制标题
重费米子超导体 UPd 2 Al 3 中 105 Pd NMR 和 NQR 信号的观测
DOI：
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
T. Kohara
中科院分区：
文献类型：
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作者：
K. Matsuda;Y. Kohori;T. Kohara
在正常态和超导态下，对重费米子超导体${mathrm{UPD}}_{2}${mathrm{Al}}_{3}进行了核磁共振和核磁共振和核磁共振测量。在反铁磁(AF)有序状态下，Pd处的内场大小约为3Koe(4.2K)。核自旋-晶格驰豫速率1/${mathm{T}}_{1}${mathrm{UPD}}_{2}${mathrm{Al}}_{3}在顺磁状态下接近温度T，在N‘eel温度下随U磁矩的临界减慢而逐渐发散，然后在AF有序态下显著下降，这可以用局域矩图很好地解释。这些结果表明，Pd原子是非磁性的，其中4d电子与U矩的耦合非常弱。在超导态，1/${mathm{T}}_{1}$与{mathm{T}}^{3}$成正比下降到0.5K，在${mathm{T}}_{mahorm{C}}$以下没有相干峰，这表明在超导能隙中出现了具有线节的各向异性超导。可以明确地证实在${mathm{UPD}}_{2}${mathm{Al}}_{3}$中AF有序和各向异性超导电性的共存。
$^{105}mathrm{Pd}$ NMR and NQR measurements have been performed both in the normal and in the superconducting states for the heavy-fermion superconductor ${mathrm{UPd}}_{2}$${mathrm{Al}}_{3}$. The magnitude of the internal field at Pd is found to be about 3 kOe (at 4.2 K) in the antiferromagnetically (AF) ordered state. The nuclear spin-lattice relaxation rate, 1/${mathrm{T}}_{1}$, in ${mathrm{UPd}}_{2}$${mathrm{Al}}_{3}$ is nearly temperature, T, independent in the paramagnetic state up to 60 K, successively diverges at N'eel temperature associated with the critical slowing down of U magnetic moments, and then decreases markedly in the AF ordered state, which is well explained by a localized moment picture. These results have shown that Pd atoms are nonmagnetic, in which 4d electrons couple very weakly to U moments. In the superconducting state, 1/${mathrm{T}}_{1}$ decreases in proportion to ${mathrm{T}}^{3}$ down to 0.5 K with no coherence peak just below ${mathrm{T}}_{mathrm{C}}$, which indicates the occurrence of anisotropic superconductivity having line nodes in the superconducting energy gap. The coexistence of the AF ordering and the anisotropic superconductivity in ${mathrm{UPd}}_{2}$${mathrm{Al}}_{3}$ could unambiguously be confirmed.