Guanxiang Du

Tunneling magnetoresistance in CoFeB∕GaAs∕(Ga,Mn)As hybrid magnetic tunnel junctions

We reported the all electronic demonstration of spin injection and detection in the trilayers with hybrid structure of CoFeB∕GaAs∕(Ga,Mn)As (metal/insulator semiconductor) by probing the magnetoresistance at low temperature from 1.8to30K. Tunneling magnetoresistance (TMR) ratios of 3.8%, 4.7%, 2.9%, and 1.4% at 1.8, 10, 20, and 30K, respectively, were observed. Bias dependence of both the junction resistance and TMR ratio was studied systematically. Vhalf at which TMR drops to half of its maximum is 6.3mV, being much smaller compared to that observed in (Ga,Mn)As∕ZnSe∕Fe and (Ga,Mn)As∕AlAs∕MnAs hybrid structures, indicating lower Fermi energy of (Ga,Mn)As.

Tunneling magnetoresistance in (Ga,Mn)As/Al-O/CoFeB hybrid structures

Tunneling magnetoresistance (TMR) in Ga(0.9)2Mn(0.08)As/Al-O/Co40Fe40B20 trilayer hybrid structure as a function of temperature from 10 to 50 K with magnetic field vertical bar H vertical bar <= 2000 Oe has been studied. TMR ratio of 1.6% at low fields at 10 K was achieved with the applied current of 1 mu A. The behavior of junction resistance was well explained by the tunneling resistance across the barrier. Strong bias dependences of magnetoresistance and junction resistance were presented

Structural Characterization and Temperature Dependence of Tunnel Magnetoresistance in Epitaxial Fe/MgO/Fe Junctions

Epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs) were grown on MgO(001) substrates by molecular beam epitaxy. The epitaxial structure has been characterized using in-situ reflection high energy diffraction, ex-situ X-ray diffraction, and high-resolution transmission electron microscopy. The magnetic and transport properties have been investigated using vibrating sample magnetometry and physical properties measurement system. The temperature dependence of the TMR ratio, whose value rises from 170% at room temperature to 318% at 10 K, is found to be nonlinear and is fitted using a model based on the effect of magnetic disorder of the electrodes on the spin polarized tunneling.