Collaborative research: Testing a new empirical law relating the efficiency of thermoremanent magnetization (TRM) and saturation magnetization (Ms)

这项工作是测试一个新的经验标度定律，表明热剩磁（TRM）的采集效率表现出功率低场依赖性，根据饱和磁化强度M（s）的不同材料的偏移量（Kletetschka等人，2004年）。新结果最显著的方面是，该定律适用于钛磁铁矿从单畴到多畴的范围。因此，虽然许多初始样本是大的和多域的，从磁铁矿的结果表明，该法律可能具有普遍的应用。研究岩石标度律的第一个关键问题是合成样品和岩石中粒子分布的退磁因子（N）的性质。在弱场磁化率的讨论中最常遇到N，其中表观磁化率可以由退磁效应强烈控制。由于退磁因子是采集过程中如此重要的一部分，在已知退磁因子的岩石中，粒子的TRM和TRM分布正在被确定。所需的关键观测是检验良好的幂律，控制其退磁因子已知的细颗粒的分布。考虑到现代磁力计的灵敏度，这可以使用相对较小且可控数量的粒子来完成。将在显微镜下检查，并将其分散在高温骨水泥中，并制备“载玻片”。 最初，避免交互，但最终将生成具有交互的分布。分散体使用强磁场进行排列，相对于该磁场，样品可以保持静止或旋转。然后用光学和扫描电子显微镜重新检查最终的合成样品。然后在不同的领域给出了ARM和TRM，并通过IRMs归一化进行了分析。对合成样品和主要岩石集合，通过IRMs归一化与经典标准双加热方法进行了古强度估计的比较。我们的结果显示了IRMs归一化方法的可能用途，并为深入研究IRMs归一化分析的基本规律提供了动力。是基于。NRM，ARM，v IRMs图决不是选择样品的唯一方法，以适合于古强度观测。然而，它们是非常简单的数据，易于阅读。热释光磁化强度（TRM）是古地磁记录的重要载体之一，因此建立一个令人信服的TRM模型对地球物理学和行星物理学具有重要意义。这样一个简单的经验规律描述了TRM的习得效率是非常显著的。月球磁性中最有趣的结果之一来自于这一想法的应用，而陨石磁性的其他可能应用也有很大的希望。这项工作是在一个优秀的研究领域的本科生工作。有一些相对常规的测量，因此它们不会被必要的实验室技术所淹没。然而，学生们知道测量必须仔细进行。学生最终还将学习大量的基本实验室技术和一些实用的电磁学。

This work is testing a new empirical scaling law showing that the efficiency of acquisition of Thermal Remanent Magnetization (TRM) exhibits a power low field dependence, with offsets for different materials according to the saturation magnetization M(s) (Kletetschka et al. 2004). The most remarkable aspect of the new results is that the law holds over the range of domain states from single domain to multidomain for titanomagnetite. Thus, although many of the initial samples were large and multidomain, the results from magnetite suggest that the law may have universal application. The first key problem in investigating the scaling law in rocks is the nature of the demagnetizing factor (N) of distributions of particles in synthetic samples and rocks. N is most often encountered in discussions of weak field susceptibility, where the apparent susceptibility can be strongly controlled by demagnetizing effects.Because the demagnetizing factor is such an important part of the acquisition process, TRM and IRM in distributions of particles is being determined in rocks whosedemagnetizing factors are known.The key observations that are required are to test the power law for well-controlled distributions of fine particles whose demagnetization factors are known. Given the sensitivity of modern magnetometers, this can be done using relatively small and controllable number of particles. They will be examined microscopically and dispersed in high temperature cement and "slides" prepared. Initially, interactions are being avoided, but eventually distribution with interactions will be generated. The dispersions are being aligned using strong magnetic fields, relative to which the sample can be kept stationary or rotated. The final synthetic samples are then reexamined with optical and scanning electron microscopy. ARM and TRM are then being given in a variety of fields and the analysis by IRMs normalization carried out.Comparison of the paleointensity estimates from IRMs normalization is done with classical standard double heating methods for the synthetic samples and the major collection of rocks available.Our results show possible uses of the IRMs normalization method and provide motivation to delve deeper in to the topic of the fundamental law that the analyses are based upon. The NRM, ARM, v IRMs plots are by no means the only means of selection of samples for suitability for paleointensity observations. However, they are quite simply obtained data and easy to read. Thermoremanent Magnetization (TRM) is one of the most important carriers of the paleomagnetic record and therefore to develop a convincing model of it has ramifications for geophysics and planetary physics. Such a simple empirical law describing the efficiency of acquisition of TRM is very remarkable. One of the most intriguing results in lunar magnetism came from an application of this idea and other possible applications in the magnetism of meteorites hold major promise. This work is in an excellent research area for undergraduate work. There are measurements of a relatively routine kind, so that they are not overwhelmed by the necessary laboratory techniques. Yet students learn that the measurements must be made carefully. Students also eventually learn plenty of basic laboratory techniques and some practical electromagnetism.