A Non-Perturbative, Low-Noise Surface Coating for Sensitive Force-Gradient Detection of Electron Spin Resonance in Thin Films.
A Non-Perturbative, Low-Noise Surface Coating for Sensitive Force-Gradient Detection of Electron Spin Resonance in Thin Films.
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一种用于薄膜中电子自旋共振灵敏力梯度检测的非微扰、低噪声表面涂层。
DOI：
10.1021/acsnano.2c08635
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发表时间：
2023
期刊：
影响因子：
17.1
通讯作者：
Marohn,JohnA
中科院分区：
文献类型：
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作者：
Boucher,MichaelC;Isaac,CorinneE;Sun,Peter;Borbat,PeterP;Marohn,JohnA
磁共振力显微镜（MRFM）的灵敏度受到表面噪声的限制。在MRFM实验中，用金属涂层薄膜聚合物样品已被证明可以通过数量级地降低样品相关的力噪声和频率噪声。利用MRFM和电感检测的电子自旋共振测量，我们发现在40nm掺氮的聚苯乙烯薄膜上热蒸发12nm的金层使氮氧化物自旋标签失活至20nm深度，使得单自旋测量变得困难或不可能。我们介绍了一种“层压样品”方案，其中金层首先在牺牲聚合物上蒸发。样品沉积在室温金层上，用溶剂去除，并手动放置在共面波导上。在低温下，使用集成了100纳米级钴尖端的高顺应性悬臂，通过amrfm检测了这种层压样品的电子自旋共振（ESR）。相对于用蒸发金属涂层制备的薄膜样品，观察到自旋信号增加了20倍。观测到的信号仍然比预期的小一些，我们讨论了可能的剩余信号损失源。
The sensitivity of magnetic resonance force microscopy (MRFM) is limited by surface noise. Coating a thin-film polymer sample with metal has been shown to decrease, by orders of magnitude, sample-related force noise and frequency noise in MRFM experiments. Using both MRFM and inductively detected measurements of electron-spin resonance, we show that thermally evaporating a 12 nm gold layer on a 40 nm nitroxide-doped polystyrene film inactivates the nitroxide spin labels to a depth of 20 nm, making single-spin measurements difficult or impossible. We introduce a “laminated sample” protocol in which the gold layer is first evaporated on a sacrificial polymer. The sample is deposited on the room-temperature gold layer, removed using solvent lift-off, and placed manually on a coplanar waveguide. Electron spin resonance (ESR) of such a laminated sample was detectedviaMRFM at cryogenic temperatures using a high-compliance cantilever with an integrated 100-nm-scale cobalt tip. A 20-fold increase of spin signal was observed relative to a thin-film sample prepared instead with an evaporated metal coating. The observed signal is still somewhat smaller than expected, and we discuss possible remaining sources of signal loss.