International Journal of Advanced Materials Research
Articles Information
International Journal of Advanced Materials Research, Vol.1, No.2, May 2015, Pub. Date: May 28, 2015
Magnetoresistance in Ferromagnet/Wide Band Gap Polymer Structures
Pages: 64-72 Views: 1327 Downloads: 401
[01] A. N. Lachinov, Bashkir State Pedagogical University, Department of Applied Physics and Nanotechnologies, Ufa, Russia; Ufa Research Centre of Russian Academy of Sciences, Ufa, Russia.
[02] N. V. Vorob’eva, Bashkir State Pedagogical University, Department of Applied Physics and Nanotechnologies, Ufa, Russia.
[03] A. A. Lachinov, Bashkir State Pedagogical University, Department of Applied Physics and Nanotechnologies, Ufa, Russia; Institute of Molecule and Crystal Physics URC RAS, Ufa, Russia.
The appearance of spintronics of polymeric materials is an important step in the development of spintronics. In the scope of this trend, it seems important to consider the possibilities of the non-traditional polymer functional materials – the polymers with a wide band gap. The results of study of the conductivity change in magnetic field for CPP (current perpendicular to the plane) geometry are presented in the current work with respect to the heterostructures containing a layer of such polymer material. Reversible electronic conductivity switching, driven by an external magnetic field, exists in the asymmetric system of Ni/polydiphenylenephthalide (film)/non-ferromagnetic metal. It is possible to change the sign of magnetoresistive phenomena by changing the magnitude of the external influence and (or) the initial electronic state of the polymeric material. The value of the threshold magnetic field for the switching of conductivity depends on the initial magnetic state of the charge-injecting ferromagnetic electrode. The phenomenon of the electronic conductivity switching of wide band gap polymer film, driven by an external magnetic field, has the character of resonance tunnelling and takes place providing that there is coincidence of the energy level of permitted states in the charge-injecting electrode and the thin energy band of coherent charge transfer in the middle of the band gap of the polymer film. The electronic conductivity switching is closely connected with partial spin polarization of current that is injected from the ferromagnet to the polymer. Evidence of spin transport is obtained in the symmetric structure of the CPP type of spin valve with polymeric spin-transport layer thickness no less than 800 nm. Theoretical models of these phenomena are discussed and the conclusion is drawn that the use of polymers with a wide band gap is certainly promising as the functional materials of spintronics.
Polymer Electronics, Spintronics, Magnetism, Magnetic Materials, Conductivity Switching
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