Department of Physics and Electronics, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
Institute for Nanofabrication Research, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
Phys Rev Lett. 2018 Apr 27;120(17):177201. doi: 10.1103/PhysRevLett.120.177201.
We perform de Haas-van Alphen (dHvA) measurements of the heavy-fermion superconductor CeCoIn_{5} down to 2 mK above the upper critical field. We find that the dHvA amplitudes show an anomalous suppression, concomitantly with a shift of the dHvA frequency, below the transition temperature T_{n}=20 mK. We suggest that the change is owing to magnetic breakdown caused by a field-induced antiferromagnetic (AFM) state emerging below T_{n}, revealing the origin of the field-induced quantum critical point (QCP) in CeCoIn_{5}. The field dependence of T_{n} is found to be very weak for 7-10 T, implying that an enhancement of AFM order by suppressing the critical spin fluctuations near the AFM QCP competes with the field suppression effect on the AFM phase. We suggest that the appearance of a field-induced AFM phase is a generic feature of unconventional superconductors, which emerge near an AFM QCP, including CeCoIn_{5}, CeRhIn_{5}, and high-T_{c} cuprates.
我们在高于上临界场的 2mK 处对重费米子超导体 CeCoIn_5 进行了德哈斯-范阿尔芬 (dHvA) 测量。我们发现，在转变温度 T_n=20mK 以下，dHvA 振幅表现出异常的抑制，同时 dHvA 频率发生位移。我们认为这种变化是由于磁场诱导的反铁磁 (AFM) 态在 T_n 以下出现而导致的磁击穿引起的，揭示了 CeCoIn_5 中磁场诱导量子临界点 (QCP) 的起源。我们发现 T_n 对 7-10T 的场依赖性非常弱，这意味着通过抑制 AFM QCP 附近的临界自旋涨落来增强 AFM 有序与磁场对 AFM 相的抑制效应相竞争。我们认为，磁场诱导 AFM 相的出现是包括 CeCoIn_5、CeRhIn_5 和高 Tc 铜酸盐在内的，在 AFM QCP 附近出现的非常规超导体的一个普遍特征。
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