Influence Of Chemical Disposal On Magnetoresistance In Chromium Dioxide Granules

Magnetoelectronics is a new field which is based on the transport of spin-polarized electrons. It modulates the conductivity of electrons by controlling another property of electrons in magnetic field—the relative orientation of spin-polarized electrons.Magnetoresistance (MR) is the important content of this field. It is the base of new generation sensor and high-density memory devices. Among the family of magnetoresistances, the tunneling magnetoresistance (TMR) has the advantage of high sensitivity and adjustable junction resistance, so it is potential to be applied in new magnetic random access memory (MRAM). Half-metal magnet CrO₂ which has full spin-polarized conduct electrons turns into the focus in the field of TMR. Many research groups in the world have been studying the magnetotransport of CrO₂. It is found that improved magnetoresistances have been obtained in complexes, such as CrO₂/Cr₂O₃, CrO₂/polymer, CrO₂/TiO₂, etc. All of those indicate that the surface properties take an important part in the magnetotransport of CrO₂ cold-pressed powders.In this paper, CrO₂ powders are treated by aqueous potassium permanganate (KMnO₄) with different time. The influence of surface properties on magnetotransport of CrO₂ granular compacts is studied. We have analyzed the CrO₂ through detecting surface components, crystalline structure and electromagnetic properties with different treatments. The results show that the change of surface Cr₂O₃ thickness induces to the difference in tunneling barrier, which alters magnetotransport properties of CrO₂.