Kotegawa H, Matsushima K, Nakahara S, Tou H, Kaneyoshi J, Nishiwaki T, Matsuoka E, Sugawara H, Harima H
Department of Physics, Kobe University, Kobe 657-8501, Japan.
J Phys Condens Matter. 2017 Jun 14;29(23):234002. doi: 10.1088/1361-648X/aa6e7d. Epub 2017 Apr 21.
We report single crystal preparation, resistivity, and nuclear quadrupole resonance (NQR) measurements for new pressure-induced superconductor CrAs. In the first part, we present the difference between crystals made by different thermal sequences and methods, and show the sample dependence of superconductivity in CrAs. In the latter part, we show NQR data focusing the microscopic electronic state at the phase boundary between the helimagnetic and the paramagnetic phases. They suggest strongly that a quantum critical point is absent on the pressure-temperature phase diagram of CrAs, because of the strong first-order character of the magnetic transition; however, the spin fluctuations are observed in the paramagnetic phase. The close relationship between the spin fluctuations and superconductivity can be seen even in the vicinity of the first-order magnetic transition in CrAs.
我们报告了新型压力诱导超导体CrAs的单晶制备、电阻率和核四极共振（NQR）测量结果。在第一部分，我们展示了通过不同热序列和方法制备的晶体之间的差异，并说明了CrAs中超导性的样品依赖性。在后面部分，我们展示了聚焦于螺旋磁相和顺磁相之间相界处微观电子态的NQR数据。这些数据强烈表明，由于磁转变的强一级特性，在CrAs的压力-温度相图上不存在量子临界点；然而，在顺磁相中观察到了自旋涨落。即使在CrAs的一级磁转变附近，也能看到自旋涨落与超导性之间的密切关系。
