The present invention is a dielectric constant with a result of the four values ​​of having a different sign from the spinel bar relates to a method of producing a dating material, in particular even more specifically, the present invention is a zero in the hysteresis curve of a dual magnetic field (zero field) magnetization ( represents the memory effect of ε), in the x- ray diffraction spot a Fe ²⁺ ions (tetrahedral ^site), V 3+ ion B-digit (octahedral sites), each location that a typical cubic _FeV 2 O 4 spinel of the the structure, giving the N temperature of the _FeV 2 O 4 powder substance in the magnetization curve shows the Ferrimagnetism characteristics observed a large irreversible phenomenon between ZFC and FC curves, and consistent with the N temperature magnetization disappears from near 109 K, FeV ₂ O to increase the magnetization is abruptly significantly in the magnetic field from the _four substances phenomenon hysteresis curve showing the memory effect in the (Jump) was observed as a phenomenon, showing the form of a 2-line in the Mossbauer spectroscopy spectrum at 109 K the temperature the same as the result of the hysteresis curve measured by a N temperature, and second size of a fine magnetic field is from 0 K vicinity commonly found in ordinary magnetic material and a maximum value continues to decrease, with increasing temperature the temperature at which a zero in the N temperatures dependency and has an effect that appears a phenomenon that can be found on any other typical material of FeV ₂ O _4.