How pressure influences the magnetic properties of titanomagnetite and iron with implications for magnetic anomalies and core fields

压力如何影响钛磁铁矿和铁的磁性，并对磁异常和核心场产生影响

• 批准号: 170001569
• 负责人: Professor Dr. Stuart Alan Gilder
• 金额: --
• 依托单位: Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik (BGI)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/170001569?language=en
• 关键词: How; pressure; influences; magnetic; properties

Pressure is an important variable in the Earth and planetary sciences, yet little is known abouthow extreme pressures influence the magnetic properties of geomaterials. Such knowledge isimportant to properly interpret magnetic anomalies and to understand how iron or iron alloys inthe solid inner core of planets interact with the magnetic fields generated in their outer cores. Wepropose to develop new high-pressure cell technology that allows us to directly measure the fullmagnetic vector of well-characterized samples as a function of pressure and temperature. Ourexperiments are intended to better understand pressure-induced changes in Curie temperatureand magnetic moment of relevant magnetic remanence carriers such as titanomagnetite andiron, including iron phases with Ni and S, with particular relevance to the cores of Earth, Marsand potentially Mercury. Numerical modelling will compliment the experiments by computingstructural and magnetic phase diagrams of iron and Fe-Ni/S alloys. The thermodynamicparameters will in part be fit to ab-initio phase diagram computations based on the clusterexpansion formalism. Magnetic ordering temperatures will be computed in the Fe and the Fe-Ni/S systems by evaluating Heisenberg Hamiltonians in the mean-field-approach and randomphase-approximation. Exchange interaction parameters for the Heisenberg Hamiltonians will beobtained by fitting ab-initio computations on magnetic structures.

压力是地球和行星科学中的重要变量，但众所周知的极端压力几乎没有影响地材料的磁性。这样的知识很重要，可以正确解释磁异常，并了解行星固体内核中的铁或铁合金如何与其外核中产生的磁场相互作用。 Wepropose开发新的高压细胞技术，使我们能够直接测量特征良好的样品的全磁性载体，这是压力和温度的函数。我们的广泛性旨在更好地理解相关磁性弹药的压力诱导的温度变化，例如钛磁铁矿和铁，包括带有Ni和S的铁相，与地球核心，Marsand潜在的汞有条。数值建模将通过铁和Fe-Ni/S合金的计算结构和磁相图来补充实验。热力学参数将部分适合基于聚类的形式主义的Ab-Initio相图计算。通过在平均野外接口和随机相关示例中评估Heisenberg Hamiltonians，将在FE和FE-NI/S系统中计算磁有序温度。 Heisenberg Hamiltonians的交换相互作用参数将通过对磁性结构进行拟合Ab-Initio计算来实现。