Magnetoresistance and spin polarization of electron current in magnetic tunnel junctions

Tunneling magnetoresistance in ferromagnetic planar hetero-nanojunctions

“…12 a maximal TMR value of 30% is obtained with $p_{{\rm F} \downarrow } /p_{{\rm F} \uparrow } = 0.3$ ; similar TMR values of 30–45% at $p_{{\rm F} \downarrow } /p_{{\rm F} \uparrow } = 0.6$ to 0.8 for $L = 0.5$ –1.0 nm can be found in Ref. 11.…”

“…At the values of $\delta _{\rm L} \simeq 0.38$ and $\delta _{\rm R} \simeq 0.47$ , which are often referred to for Fe or FeCo ferromagnets (see for example Refs. 11, 16–18), the magnitude of the TMR at zero bias reaches 200–250%. At high voltages, the TMR reveals an oscillatory behavior similar to that predicted in Refs.…”

“…The previous theoretical investigations of the TMR effect 9–13 have been concentrated mainly on magnetic planar structures built with the same metallic ferromagnetic electrodes, and where the dielectric layer was of the Al 2 O 3 and MgO type as usual. For semiconducting heterostructures, the case of different magnetic electrodes was considered, too 14.…”

Spin-polarized tunneling through randomly transparent magnetic junctions: Reentrant magnetoresistance approaching the Jullière limit

“…4 In particular, among various theoretical studies of spin-polarized transport, a large body of work has aimed at developing adequate models for the tunneling magnetoresistance in singleparticle approximation, [5][6][7][8][9][10][11][12] by accounting for many-body effects due to electron-magnon interactions in normal [13][14][15][16][17] and superconducting 18,19 states, and the influence of disorder. [20][21][22][23] The subject of the present study is the tunneling magnetoresistance ͑TMR͒ effect originating from the dependence of the tunneling current on the relative orientation of the magnetizations in two electrodes separated by a thin insulating layer.…”

Low potential barrier height effects in magnetic tunneling junctions

“…More recently, extensions of Slonczewski's model 8 for finite bias [9][10][11] have shown that the TMR is a function of the potential barrier height and this dependence can lead to TMR inversion for low enough barrier and large electron effective mass. 12,13 Experimental evidences have been observed in systems with TaO x barriers. 14 To approach the effects of barrier height and thickness over the magnetoresistance, an adequate determination of these quantities is crucial.…”