Dataset reporting measurements of shot noise of tunneling current in La2-xSrxCuO4/La2CuO4/La2-xSrxCuO4 (LSCO/LCO/LSCO) heterostructures

This dataset presents shot-noise measurements performed on LSCO-based tunnel junctions, in order to identify causes of the pseudogap associated with high-temperature superconductivity in copper oxides. The data reports measurements of shot noise of tunneling current in high-quality La2-<i>x</i>Sr<i>x</i>CuO4/La2CuO4/La2-<i>x</i>Sr<i>x</i>CuO4 (LSCO/LCO/LSCO) heterostructures fabricated using atomic-layer-by-layer molecular beam epitaxy, at four doping levels. In the study, ALL-MBE was used to synethesise trilayer LSCO/LCO/LSCO films with LSCO doping level of <i>x </i>= 0.10, 0.12, 0.14, and 0.15, with film transition temperates of 28 K, 34 K, 37 K, and 38 K. Energy dispersive x-ray spectroscopy and atomic-resolution electron-energy-loss spectroscopy were used for La, Sr, and Cu elemental mapping. From these heterostructures, fabricated tunnel junction devices were fabricated using photolithography. Precision measurements of the bias dependence of the differential conductance (<i>G </i>= d<i>I</i>/d<i>V</i>, where <i>I </i>is the current and <i>V </i>is the voltage bias) were then performed using standard lock-in techniques. Two tunnel junctions were measured at each LSCO doping level in the top and bottom superconducting electrodes. The dataset consists of a single compressed <b>.rar</b> archive, with eight subdirectories. Each subdirectory includes between 800-1100 files, with the data contained in each available in both <b>.dat</b> and <b>.csv</b> format. Each subdirectory used the naming convention “lsco0pxxsn” where “xx” indicates the doping level of the La(2-x)Sr(x)CuO4 layers and n indicates either device 1 or device 2 for each doping. The data within the subdirectories is as follows: <b>lsco0p10s1</b> (doping level .10, device 1)<b>lsco0p10s2 </b>(doping level .10, device 2)<b>lsco0p12s1 </b>(doping level .12, device 1)<b>lsco0p12s2 </b>(doping level .12, device 2)<b>lsco0p14s1 </b>(doping level .14, device 1)<b>lsco0p14s2 </b>(doping level .14, device 2)<b>lsco0p15s1</b> (doping level .15, device 1)<b>lsco0p15s2 </b>(doping level .15, device 2). Each subdirectory contains four file types: <b>.dat</b> files with filenames in the format “tt.00K_xxxxV.dat”. These are the raw data from the measurements of voltage noise, labeled by the temperature tt in Kelvin, and xxxx is the dc bias voltage applied to the series combination of the sample plus 380 kOhms of series resistance. These are two-column files. The first column is the frequency bin (Hz) and the second column is the voltage noise after the cross correlation (arb units set by the voltage gain of the preamplifiers; proportional to V^2/Hz). <b>.csv</b> files which represent the same data as the .<b>dat</b> files above. <b>.dat</b> files with filenames in the format “ttK_didv4noise.dat”. These contain the measured differential conductance data associated with each temperature, needed for fitting the frequency dependence of the noise. These files are five columns. The first column is the dc bias voltage across the sample itself, in volts. The third column is the dc current through the sample in Amps. The fifth column is the differential conductance in Siemens. (The second and fourth columns are lock-in readings in arb units used to calculate the fifth column.) A single <b>.xls</b> file, containing the fit parameters obtained from the R_sC_p fitting analysis for each bias, with a separate sheet for each temperature. There are four columns for each temperature. Column 1 is the dc bias (in volts) applied across the series combination of the sample + 380 kOhms of series resistance. Column 2 is the fit magnitude of the voltage noise (in arb units). Column 3 is the noise magnitude converted into current noise, units of A^2/Hz, using the dI/dV at that bias. Column 4 is the R_sC_p fit parameter. <b>.rar</b> files can be opened using open source decompression software, for example 7-Zip. <b>.dat</b> files can be opened using text processing software. The .<b>csv</b> and .<b>xls</b> files can be opened using open source spreadsheet software such as OpenOffice Calc. <br>

本数据集针对基于镧锶铜氧化物（LSCO，La₂₋ₓSrₓCuO₄）的隧道结开展散粒噪声测量，旨在探明铜氧化物高温超导体中赝能隙的相关成因。本数据集记录了采用逐层原子分子束外延技术制备的高质量La₂₋ₓSrₓCuO₄/La₂CuO₄/La₂₋ₓSrₓCuO₄（LSCO/LCO/LSCO）异质结构在四种掺杂浓度下的隧穿电流散粒噪声测量结果。
本研究采用全逐层原子分子束外延（ALL-MBE）技术合成了LSCO/LCO/LSCO三层薄膜，其中LSCO的掺杂浓度x分别为0.10、0.12、0.14和0.15，对应的薄膜转变温度分别为28 K、34 K、37 K和38 K。研究采用能量色散X射线能谱与原子分辨电子能量损失能谱对La、Sr、Cu元素进行了元素测绘。基于上述异质结构，研究人员通过光刻工艺制备了隧道结器件。随后采用标准锁相放大技术，对微分电导（G = dI/dV，其中I为电流，V为偏置电压）随偏置的依赖关系进行了精密测量。针对每个LSCO掺杂浓度，分别对上下超导电极中的两个隧道结开展了测量。
本数据集仅包含一个压缩<b>.rar</b>归档文件，内含8个子目录。每个子目录包含800~1100个文件，数据同时以<b>.dat</b>和<b>.csv</b>格式存储。所有子目录均遵循"lsco0pxxsn"的命名规则：其中"xx"代表La₂₋ₓSrₓCuO₄层的掺杂浓度，"n"则代表对应掺杂浓度下的器件编号（1或2）。各子目录对应的内容如下：<b>lsco0p10s1</b>（掺杂浓度0.10，器件1）、<b>lsco0p10s2</b>（掺杂浓度0.10，器件2）、<b>lsco0p12s1</b>（掺杂浓度0.12，器件1）、<b>lsco0p12s2</b>（掺杂浓度0.12，器件2）、<b>lsco0p14s1</b>（掺杂浓度0.14，器件1）、<b>lsco0p14s2</b>（掺杂浓度0.14，器件2）、<b>lsco0p15s1</b>（掺杂浓度0.15，器件1）、<b>lsco0p15s2</b>（掺杂浓度0.15，器件2）。
每个子目录包含四类文件：第一类为格式为"tt.00K_xxxxV.dat"的<b>.dat</b>文件，存储电压噪声测量的原始数据：文件名中的tt代表测试温度（单位为开尔文），xxxx代表施加于样品与380 kΩ串联电阻组合两端的直流偏置电压。此类文件为双列数据：第一列为频率区间（单位：Hz），第二列为互相关处理后的电压噪声（任意单位，由前置放大器电压增益标定，与V²/Hz成正比）。第二类为<b>.csv</b>文件，存储与上述<b>.dat</b>文件完全一致的数据。第三类为格式为"ttK_didv4noise.dat"的<b>.dat</b>文件，存储对应温度下的微分电导测量数据，用于拟合噪声的频率依赖性。此类文件为五列数据：第一列为样品两端的直流偏置电压（单位：V），第三列为流过样品的直流电流（单位：A），第五列为微分电导（单位：S）（第二列与第四列为锁相放大器读取的任意单位数值，用于计算第五列数据）。第四类为单个<b>.xls</b>文件，内含针对每个偏置点通过RₛCₚ拟合分析得到的参数，每个温度对应一个独立工作表。每个工作表包含四列数据：第一列为施加于样品+380 kΩ串联电阻组合两端的直流偏置电压（单位：V）；第二列为电压噪声的拟合幅值（任意单位）；第三列为通过该偏置点的dI/dV转换得到的电流噪声幅值（单位：A²/Hz）；第四列为RₛCₚ拟合参数。
可通过开源解压软件（例如7-Zip）打开<b>.rar</b>归档文件；<b>.dat</b>文件可通过文本处理软件打开；<b>.csv</b>与<b>.xls</b>文件可通过开源电子表格软件（例如OpenOffice Calc）打开。