论文标题
疾病和磁场在二维TA $ _X $（SIO $ _2 $）$ _ {1-x} $粒状胶片中引起的玻色金属状态
Disorder and magnetic field induced Bose-metal state in two-dimensional Ta$_x$(SiO$_2$)$_{1-x}$ granular films
论文作者
论文摘要
二维超导体材料中中间异常金属状态的起源仍然是神秘的。在本文中，我们以一系列$ \ sim $ 9.0 nm厚的ta $ _x $（sio $ _2 $）$ _ {1-x} $（$ x $是ta的体积分数）纳米胶片的一系列状态。在零场，$ x $ $ \ gtrsim $ 0.75的电影会经历一部berezinskii-kosterlitz-无尽的过渡，从冷却后从正常状态到超大状态。对于$ x $ $ \ lyssim $ 0.71胶卷，随着温度从2 K降低到40 mk，电阻会增加。在$ x $ $ \ simeq $ 0.73胶片中，即在过渡温度附近，胶片的阻力在冷却时急剧降低，即在冷却时急剧下降，就好像该系统越过超导状态一样，但随后的饱和度比正常状态少得多。当应用垂直于膜平面的小磁场时，异常的金属状态发生在$ x $ $ \ gtrsim $ 0.75胶片中。发现疾病和磁场都可以诱导从超导体到异常金属的过渡，并且它们对过渡的影响相似。对于磁场引起的情况，我们发现板电阻$ r _ {\ square}（t，h）$（$ t $和$ h $是温度和磁场的大小）数据附近，从异常金属到超导体到超导体到超级导体，以及在异常金属到无异常的属性过渡的范围，分别遵守独特的属性，以遵守独特的定义。我们的结果强烈表明，在TA $ _X $（SIO $ _2 $）中的异常金属状态$ _ {1-x} $粒状膜是波斯型和动力学轨迹场的波动，这是由超导量子波动引起的，在其形成中起着关键的作用。
The origin of the intermediate anomalous metallic state in two-dimensional superconductor materials remains enigmatic. In the present paper, we observe such a state in a series of $\sim$9.0 nm thick Ta$_x$(SiO$_2$)$_{1-x}$ ($x$ being the volume fraction of Ta) nanogranular films. At zero field, the $x$ $\gtrsim$ 0.75 films undergo a Berezinskii-Kosterlitz-Thouless transition as transform from normal to superconducing states upon cooling. For the $x$ $\lesssim$ 0.71 films, the resistance increases with decreasing temperature from 2 K down to 40 mK. A normal state to anomalous metallic state transition is observed in the $x$ $\simeq$ 0.73 film, i.e., near the transition temperature, the resistance of the film decreases sharply upon cooling as if the system would cross over to superconducting state, but then saturates to a value far less than that in normal state. When a small magnetic field perpendicular to the film plane is applied, the anomalous metallic state occurs in the $x$ $\gtrsim$ 0.75 films. It is found that both disorder and magnetic field can induce the transition from superconductor to anomalous metal and their influences on the transition are similar. For the the magnetic field induced case, we find the sheet resistance $R_{\square}(T,H)$ ($T$ and $H$ being the temperature and the magnitude of magnetic field) data near the crossover from the anomalous metal to superconductor and in the vicinity of the anomalous metal to insulator transition, respectively, obey unique scaling laws deduced from the Bose-metal model. Our results strongly suggest that the anomalous metallic state in the Ta$_x$(SiO$_2$)$_{1-x}$ granular films is bosonic and dynamical gauge field fluctuation resulting from superconducting quantum fluctuations plays a key role in its formation.
