Rock magnetism is a branch of geophysics and paleomagnetism that studies the magnetic properties of rocks, sediments, and soils. It focuses on how these materials acquire and retain magnetic signals, which can provide valuable information about the Earth's past magnetic field and geological history. Key aspects of rock magnetism include: 1. **Remanent Magnetization**: Many rocks acquire a permanent magnetization that reflects the Earth's magnetic field at the time the rocks were formed.
Remanence, also referred to as remanent magnetization, is a phenomenon in magnetism that describes the residual magnetization of a material after an external magnetic field has been removed. When certain materials, particularly ferromagnetic materials (like iron, cobalt, and nickel), are exposed to a strong magnetic field, they can become magnetized. Once the external field is removed, these materials can retain a part of that magnetization, which is what we call remanence.
The Stoner-Wohlfarth model is a theoretical framework used to describe the magnetic behavior of ferromagnetic materials, particularly concerning their hysteresis and magnetic switching properties. It was formulated in the 1960s by physicists E. C. Stoner and E. P. Wohlfarth.
The Verwey transition refers to a first-order phase transition observed in magnetite (Fe₃O₄), a mixed-valence iron oxide that exhibits a change in its electrical and magnetic properties at a specific temperature, typically around 120 K (−153 °C). At temperatures above the Verwey transition, magnetite behaves as a good conductor, while below this temperature, it becomes an insulator.
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