Vortex-induced quantum metallicity in the mono-unit-layer superconductor NbSe2
Vortex-induced quantum metallicity in the mono-unit-layer superconductor NbSe2
复制标题
DOI：
10.1103/physrevb.99.220501
复制
发表时间：
2019-06-05
影响因子：
3.7
通讯作者：
Hasegawa, Shuji
中科院分区：
文献类型：
--
作者：
Ichinokura, Satoru;Nakata, Yuki;Hasegawa, Shuji
我们在超高真空环境中进行了原位磁电阻测量，以揭示在双层石墨烯上外延生长的单单位层NbSe 2的量子相变。结果表明，由表面正常磁场引起的超导-正常态转变是由准金属态介导的。这种行为是一致的“玻色金属”的图片，其中有限的耗散是由于强烈的规范场波动的相位相干性的破坏所造成的。一方面，在平均场临界温度附近，从正常态到低温态的转变开始受到振幅涨落效应的影响，在磁场下尤为显著。我们应用标度理论来确定相边界。标度分析的结果揭示了一个复杂的，但本质的二维超导体单层NbSe 2的相图。
We performed in situ magnetoresistance measurements in the ultrahigh-vacuum environment to reveal the quantum phase transitions of single unit-layer NbSe2 epitaxially grown on bilayer graphene. It was found that the superconductor-normal state transition caused by the surface-normal magnetic field was intermediated by a quasimetallic state. This behavior is consistent with the "Bose metal" picture where a finite dissipation is caused by the breaking of phase coherence due to strong gauge-field fluctuation. On one hand, around the mean-field critical temperature, the onset of transition from the normal state to the low-temperature states was governed by the amplitude-fluctuation effect, prominently under the magnetic field. We applied scaling theories to determine the phase boundaries. The result of scaling analyses revealed a complex but essential phase diagram of the single unit-layer NbSe2 as a two-dimensional superconductor.