爱丁堡大学Wyn Williams教授学术报告

地球系统科学论坛第683期

应best365英国体育在线王华沛教授邀请，爱丁堡大学Wyn Williams教授来校访问并做学术报告。

报告时间：11月8日（周五）上午9:00

报告地点：主楼412

报告题目：From Here to Eternity: Stability of Single-Vortex Domain States 

报告人简介：

1979-82: Undergrad in Physics at Imperial College

1982-86: PhD ‘The effect of time and temperature on magnetic remanence’ Cambridge University

1986-89: Post-Doc with David Dunlop at Toronto University

1989-2002: Lecturer at Edinburgh University

2002 – present: Professor of Mineral Magnetism, Edinburgh University 

报告内容简介：

Magnetic nano and micro particles are used in a wide range of applications including environmental remediation, medical therapies and configurable memory devices. Applications in Earth sciences rely of the ability of fine magnetic particles to record changes in the geomagnetic field and hold these for billions of years, and provides one of the few ways in which we can probe the evolution of the of Earth and other planetary bodies.

Critical to the fidelity of palaeomagnetic recordings, and generally independent of mineralogy, is the characteristic behaviour of domain structures with the magnetic minerals. Hitherto these have been categorized as either Single-Domain (SD), Pseudo-Single-Domain (PSD) and Multidomain (MD) states. With the advent of numerical micromagnetic modelling and high-resolution electron holographic imaging, it has been shown that the dominant palaeomagnetic recorder is none of these, but is rather a single-vortex (SV) state and which exhibits high magnetic remanence and with high thermal stability that often exceeds that of SD states.

In this presentation we will examine the evolution of domain states with grain size from SD to SV and Multi-Vortex states and structures with true MD characteristics. We will assess the ability of SV domain states to explain the observed PSD remanences, thermal stabilities and coercivities. Finally, will speculate on the ability of SV states to yield high fidelity paleomagnetic recordings as well as their possible contribution to paleomagnetic uncertainties introduced by non-ideal recording behaviour.

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2019年11月