Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature

Abstract

[1] Low-temperature magnetization of hematite within the basal plane has been studied in a collection of natural crystals by means of torque magnetometry. Comparison between the torque curves at room temperature and at 77 K allows identification of a weak ferromagnetic moment constrained within the basal plane at temperatures well below the Morin transition. Annealing the samples produces the expected reduction of the weak ferromagnetic moment, but there is also a relationship between the ferromagnetic moment before and after annealing. Low-temperature measurements after the annealing experiment reveal the presence of a weak ferromagnetic moment that survives the annealing. This observation suggests the magnetic structure of natural hematite crystals below the Morin transition can still be a carrier of magnetization. Martin-Hernandez, F., and A. M. Hirt (2013), Evidence for weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperature,

Hysteresis and coercivity of hematite

“…4–5, Figure ] show that only part of the low‐temperature moment can be annealed out; annealing apparently reduces the number of strain centers but does not remove all of them. Similar results are reported by Martín‐Hernández and Hirt [].…”

Exfoliation of hematite: Morphological, structural and magnetic investigations

“…There is substantial literature on the magnetic properties [1, 13,14] and Mössbauer [13,15] spectra of natural and synthetic hematite nanoparticles. It is generally found that the Morin transition moves to lower temperature with reduced particle size and that it is sharply reduced in particles smaller than about 100 nm [13].…”

A simple solid-state method to synthesize nanosized ferromagnetic $$\upalpha $$-$$\hbox {Fe}_{2}\hbox {O}_{3}$$ with enhanced photocatalytic activity in sunlight

“…The phenomenon of magnetism in hematite was explained by Zubov et al [5] based on the investigation of natural faces of the hematite band calculating the energy of surface anisotropy for the faces of types (100) and (111). Weak ferromagnetic moment within the basal plane of hematite natural crystals at low temperatures was explained by Hernandez [6].…”