GMR Based Spin Valve like Magnetic Diode Exploiting Negative JMR in Heusler Alloy Thin Film/Semiconductor Heterostructures

Abstract

Room temperature spin valve like magnetic diode behavior has been found in Co2MnSi/SiO2/n-Si heterostructure. The Co2MnSi (CMS) Heusler alloy film has been grown on n type Si (001) substrate with the help of Electron Beam Physical Vapour Deposition technique. We have investigated the transport properties of our heterostructure at various isothermal conditions in the temperature regime of 78-300 K. From the current (I) – voltage (V) characteristics of the junction, excellent rectifying tunnel diode like behavior have been seen near room temperature. The current (I) across the junction has been found to be increased with the application of magnetic B-field parallel to the CMS film clearly indicating negative Junction Magnetoresistance (JMR) of the heterostructure. It has been found to be negative 80% at 300 K at a magnetic field of 0.5 Tesla. When forward dc bias is applied to the heterostructure, the I-V characteristics are greatly influenced on turning on the field B = 0.5 T at 300 K, and the current reduces to the equal order of the magnitude of the reverse bias current. Hence our CMS/SiO2/n-Si heterostructure can perform in off (Ioff)/on (Ion) states with the use of zero/nonzero magnetic field like a spin valve at room temperature (300 K).