Figure 3: TEM images of magnetite particles in exposure experiments into magnetic fields. | Nature Communications

Figure 3: TEM images of magnetite particles in exposure experiments into magnetic fields.

From: Vortex magnetic structure in framboidal magnetite reveals existence of water droplets in an ancient asteroid

Figure 3

Images of a part of a framboidal magnetite from the Tagish Lake meteorite were recorded by a Hitachi HF3300-EH with an acceleration voltage of 300 kV. (a) Bright field image after deposition of amorphous carbon on the sample to avoid rotation during a series of experiments. Two triangles show the carbon layer of a brighter contrast than magnetite particles. (b) Schematic showing the discrimination of individual magnetite particles with labels A and B. (c) Reconstructed phase distribution of (a) in non-magnetic field after subtracted internal potential. Each particle shows a concentric circular magnetic field and a closed (that is, vortex) structure. The yellow and red arrows indicate the directions of the magnetization vectors in the magnetite particle; yellow: clockwise (particle A); red: counterclockwise (particle B). (d) Colour wheel map of the magnetization direction obtained from the reconstructed phase image (c). The white arrows in the wheel show the direction of the magnetization. Colour changes in the profiles of the magnetite (d,f and h) indicate the direction of the magnetization. (e) Reconstructed phase distribution of the magnetite particles in a magnetic field of 0.12 T to the opposite direction of electron beam after subtracted internal potential showing that each particle still has a concentric circular magnetic field and a closed (that is, vortex) structure. (f) Colour wheel map of the magnetization direction obtained from the reconstructed phase image (e). (g) Reconstructed phase distribution of the magnetite particles in non-magnetic field, but after exposure the sample to a strong ‘in-plane’ magnetic field of 1.9 T for 5 min to the direction indicated by an arrow. Internal potential has been subtracted. Both particles still have a concentric circular magnetic field and a closed (that is, vortex) structure. (h) Colour wheel map of the magnetization direction obtained from the reconstructed phase image (g). The scale bar in (a) is 200 nm.

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