Spontaneous magnetization generated by spin, pulsating, and planar combustion synthesis

Abstract

The motion of the high temperature front during combustion synthesis of ferrite materials generates residual magnetization in cylindrical product samples. The combustion wave created a current density of up to 10 A/cm2, which influenced the magnetization distribution. The measured peak magnetic field intensity was up to 8 μT. Qualitatively different magnetic field maps were generated in ferrite samples synthesized by different combustion modes. The average magnetization vector generated by either planar or pulsating combustion was oriented at a smaller angle with respect to the pellet axis (φ⩽45°) than those generated by spin combustion (60°⩽φ⩽80°). We estimate that an internal transient magnetic field of up to 5 mT formed in the postcombustion region when its temperature was below the Curie temperature. This explains why the Earth's field had no impact on the spontaneous magnetization field. Model calculations reproduce the qualitative features of the measured field maps.