适用于干稀释制冷机的可冷插入扫描探针显微镜：具备皮米级稳定性与极低温电子温度
A cold-insertable scanning probe microscope for dry dilution refrigerators with picometer stability and ultra-low electron temperatures
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中文总结 AI 辅助
本文研发了一种适用于干稀释制冷机的可冷插入扫描探针显微镜，通过双管齐下的设计策略实现皮米级稳定性与60 mK以下电子温度，突破了干式制冷机中高分辨率扫描探针技术的瓶颈。
中文摘要 AI 辅助
研究量子材料的微观机制需要基于原子力显微镜（AFM）的高分辨率扫描探针技术。然而，在无制冷剂稀释制冷机中实现具备皮米级稳定性的AFM面临两大挑战：一是脉冲管机械噪声极强，其噪声谱密度$S_{\rm PT}(f)\approx10^{-6}\\,\text{m}/\sqrt{\text{Hz}}$；二是将压电运动台热至100 mK以下存在固有权衡问题。本文展示了一种集成于标准可冷插入探针的基于AFM的扫描微波阻抗显微镜，成功突破该瓶颈。通过采用双管齐下的设计策略——将机械刚性AFM模块与磁场兼容、临界阻尼的内部弹簧悬挂结构耦合，我们实现了极低的针尖-样品相对振动噪声密度，$S_{\rm AFM}(f)<10^{-11}\\,\text{m}/\sqrt{\text{Hz}}$。这对应频谱积分后的针尖-样品相对位移$\Delta z\approx10\\,\text{pm}$，相比近期快速加载的干式SPM装置，稳定性提升超100倍。同时，优化的热接口、定制铜绑带及全面的射频滤波，使样品局部电子温度达到$T_{\rm e}\leq 60\\,$mK，规避了机械去耦带来的热损耗。该坚固的模块化架构无需对主机制冷机进行永久性结构改造，为适配其他扫描探针技术提供了便捷框架，可加速在干式制冷机中对脆弱量子相的皮米级稳定性探索。
英文摘要
Investigating the microscopic mechanisms of quantum materials requires high-resolution scanning probe techniques, often based on atomic force microscopy (AFM). However, implementing AFM in cryogen-free dilution refrigerators with picometer stability is challenged by intense pulse tube mechanical noise ($S_{\rm PT}(f)\approx10^{-6}\,\text{m}/\sqrt{\text{Hz}}$) and the fundamental trade-off with thermalizing piezoelectric motion stages below 100\,mK. Here, we demonstrate an AFM-based scanning microwave impedance microscope integrated onto a standard cold-insertable probe that successfully resolves this bottleneck. By employing a two-pronged design strategy---coupling a mechanically stiff AFM module with a magnetic-field-compatible, critically damped internal spring-suspension---we achieve an extremely low relative tip-sample vibration noise density of $S_{\rm AFM}(f)<10^{-11}\,\text{m}/\sqrt{\text{Hz}}$. This yields a spectrally integrated relative tip-sample displacement of $Δz\approx10\,\text{pm}$, representing a greater than 100-fold stability improvement over recent fast-loading dry SPM setups. Simultaneously, optimized thermal interfaces, customized copper strapping, and comprehensive RF filtering enable a local sample electron temperature of $T_{\rm e}\leq 60\,$mK, circumventing the thermal penalties of mechanical decoupling. By avoiding permanent structural modifications to the host cryostat, this robust, modular architecture provides an accessible framework for adapting other scanning probe techniques, accelerating the exploration of fragile quantum phases in dry cryostats with picometer stability.
