Micromagnetic Simulations of Chemical Remanent Magnetization Acquisition in Single‐Vortex Magnetite Particles

Abstract Magnetic minerals can preserve remanent magnetization to provide ancient magnetic field records. Although thermoremanent magnetization (TRM) is well understood, chemical remanent magnetization (CRM) from chemical processes is also prevalent in nature and can complicate TRM records by introducing additional remanence signals. Previous studies show that CRM in single‐domain (SD) particles can lead to paleointensity underestimates. However, most natural magnetic particles are non‐uniformly magnetized, such as in the single‐vortex (SV) states, whose CRM mechanism remains unclear. Using micromagnetic modeling, we investigate CRM acquisition in fine‐grained magnetite during grain growth processes. We show that the CRM in SV particles is nearly linear with the external magnetic fields below 100 μT, within typical terrestrial magnetic fields. Unlike SD particles, SV particles show stronger CRM compared to TRM, which could potentially bias to higher paleointensity estimates. These findings highlight the importance of considering non‐uniform domain states when interpreting CRM records in paleomagnetic studies.