Electric and Magnetic Field Tunable Rectification and Magnetoresistance in Fe _x Ge _{1− x} /Ge Heterojunction Diodes

Abstract

Fe𝑥Ge1−𝑥/Ge amorphous heterojunction diodes with p-Fe𝑥Ge1−𝑥 ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type, n-type and intrinsic semiconductors, respectively. The 𝐼-𝑉 curves of p-Fe0.4Ge0.6/p-Ge diodes only show slight changes with temperature or with magnetic field. For the p-Fe0.4Ge0.6/n-Ge diode, good rectification is maintained at room temperature. More interestingly, the 𝐼-𝑉 curve of the p-Fe0.4Ge0.6/i-Ge diode can be tuned by the magnetic field, indicating a large positive magnetoresistance. The resistances of the junctions decrease with the increasing temperature, suggesting a typical semiconductor transport behavior. The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the energy band structures of the interface.

Effect of thermal deformation on giant magnetoresistance of flexible spin valves grown on polyvinylidene fluoride membranes

“…On the other hand, Fe 81 Ga 19 (FeGa) alloy which exhibits the largest magnetostriction (∼ 350 ppm for the typical bulk) among the various alloys not containing rare earth elements has been extensively applied as engineering materials in strain sensors and actuators. [21][22][23][24] The combination of FeGa alloy and PVDF membrane is a model system to investigate the influence of thermal deformation on the magnetic properties of magnetic films. Previously in FeGa/PVDF films we realized the enhancement of magnetic anisotropy with increasing temperature by utilizing the anisotropic thermal deformation of PVDF.…”