Ultra-high sensitivity moment magnetometry of geological samples using magnetic microscopy: ULTRA-SENSITIVE MOMENT MAGNETOMETRY
Ultra-high sensitivity moment magnetometry of geological samples using magnetic microscopy: ULTRA-SENSITIVE MOMENT MAGNETOMETRY
复制标题
使用磁显微镜对地质样品进行超高灵敏度矩磁测量：ULTRA-SENSITIVE MOMENT MAGNETOMETRY
DOI：
10.1002/2016gc006487
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Weiss, Benjamin P.
中科院分区：
文献类型：
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作者：
Lima, Eduardo A.;Weiss, Benjamin P.
有用的古地磁信息预计将由力矩比标准超导岩石磁强计的探测下限低三个数量级的样品记录下来。这类样品现在可以使用最近开发的磁性显微镜来探测，这种显微镜以前所未有的空间分辨率和场灵敏度绘制出室温样品上方的磁场。然而，实现这一潜力需要开发从磁性显微镜数据中检索样品矩的技术。基于这一目标，我们开发了一种从未分辨或几乎未分辨的磁化强度图中唯一地获得地质样品的净磁矩的技术。这项技术对于分析微小的弱磁化样品特别有效，例如陨石球粒陨石和像锆石这样的陆地硅酸盐晶体。我们通过将其应用于从合成源生成的场图以及使用超导量子干涉装置(SQUID)显微镜在地质样品上方测量的场图来验证这一技术，力矩低至10−15Am2。对于大多数磁性岩石样品，从SQUID显微镜数据估计的净磁矩与使用较低灵敏度的标准岩石磁强计获得的独立磁矩测量的误差在之内。除了具有优异的力矩灵敏度外，SQUID显微镜净力矩磁测还能够识别和隔离磁污染和背景源，这对于提高弱磁性样品古地磁研究的准确性至关重要。
Useful paleomagnetic information is expected to be recorded by samples with moments up to three orders of magnitude below the detection limit of standard superconducting rock magnetometers. Such samples are now detectable using recently developed magnetic microscopes, which map the magnetic fields above room‐temperature samples with unprecedented spatial resolutions and field sensitivities. However, realizing this potential requires the development of techniques for retrieving sample moments from magnetic microscopy data. With this goal, we developed a technique for uniquely obtaining the net magnetic moment of geological samples from magnetic microscopy maps of unresolved or nearly unresolved magnetization. This technique is particularly powerful for analyzing small, weakly magnetized samples such as meteoritic chondrules and terrestrial silicate crystals like zircons. We validated this technique by applying it to field maps generated from synthetic sources and also to field maps measured using a superconducting quantum interference device (SQUID) microscope above geological samples with moments down to 10−15Am2. For the most magnetic rock samples, the net moments estimated from the SQUID microscope data are within error of independent moment measurements acquired using lower sensitivity standard rock magnetometers. In addition to its superior moment sensitivity, SQUID microscope net moment magnetometry also enables the identification and isolation of magnetic contamination and background sources, which is critical for improving accuracy in paleomagnetic studies of weakly magnetic samples.