离子束辅助溅射生长的ZrN薄膜中无序驱动的输运
Disorder-driven transport in ZrN thin films grown by ion-beam-assisted sputtering
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- Argonne National Laboratory（阿贡国家实验室）
- Drexel University（德雷塞尔大学）
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中文总结 AI 辅助
本研究通过离子束辅助溅射生长ZrN薄膜，系统调控生长条件实现从金属到绝缘的输运转变，发现绝缘态符合三维Mott变程跳跃，超导转变温度与无序脱耦，相边界由自由指数幂律描述，确立了可调平台。
中文摘要 AI 辅助
我们研究了通过直流离子束辅助溅射（IBAS）生长的氮化锆（ZrN）薄膜的结构和电子输运性质，作为氮分压、溅射功率和沉积温度的函数。生长条件的变化使得能够从无序金属和超导行为可控地调节到绝缘输运。增加氮气流导致薄层电阻增加、超导转变温度受到抑制以及非金属导电。XRD显示长程结晶度或有序性没有可测量的变化。在绝缘区域，低温输运很好地由三维Mott变程跳跃（VRH）描述，其特征温度$T_0$随薄层电阻单调增加，跨越四个数量级。尽管$T_0$与无序之间存在这种强相关性，$T_c$却对$T_0$没有表现出系统的依赖性，表明局域化物理与超导能标之间脱耦。磁输运测量不能由标准BCS模型或脏极限II型Werthamer-Helfand-Hohenberg模型很好地描述。相边界反而由自由指数幂律$\u03bc_0 H_{c2}(T) = \u03bc_0 H_{c2}(0)[1 - (T/T_c)^{n}]$捕获，其中$n \approx 3.47$，并外推到$\u03bc_0 H_{c2}(0) \approx 6.4$ T。薄膜的相干长度约为7 nm。这些结果确立了IBAS生长的ZrN作为一个广泛可调的平台，用于研究无序驱动的输运以及金属导电、电子局域化和超导性之间的交叉。
英文摘要
We investigate the structural and electronic transport properties of zirconium nitride (ZrN) thin films grown by dc ion-beam assisted sputtering (IBAS) as a function of nitrogen partial pressure, sputtering power and deposition temperature. Variation of growth conditions enables controlled tuning from disordered metallic and superconducting behavior to insulating transport. Increasing nitrogen flow drives an increase in sheet resistance, suppression of superconducting transition temperature, and non-metallic conduction. XRD shows no measurable change in long range crystallinity or order. In the insulating regime, low-temperature transport is well described by 3D Mott variable-range hopping (VRH), with the characteristic temperature $T_0$ increasing monotonically with sheet resistance over four orders of magnitude. Despite this strong correlation between $T_0$ and disorder, $T_c$ exhibits no systematic dependence on $T_0$, indicating a decoupling between localization physics and the superconducting energy scale. Magnetotransport measurements are not well described by the standard BCS model nor the dirty type-II Werthamer-Helfand-Hohenberg model. The phase boundary is instead captured by a free-exponent power law, $μ_0 H_{c2}(T) = μ_0 H_{c2}(0)[1 - (T/T_c)^{n}]$ with $n \approx 3.47$, and extrapolates to $μ_0 H_{c2}(0) \approx 6.4$ T. The films have an extracted coherence length of 7 nm. These results establish IBAS-grown ZrN as a broadly tunable platform for investigating disorder-driven transport and the crossover between metallic conduction, electronic localization, and superconductivity.
