Abstract
We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds.
Highlights
Recent discoveries in the ferromagnet/insulator/ferromagnet (FM/I/FM) magnetic tunnel junctions (MTJs) have demonstrated that the relative orientation of the two FM electrodes can be either altered by an external magnetic field, i.e. the tunneling magnetoresistance (TMR) effect[1], or controlled by a spin-polarized current, i.e. the current-induced magnetization reversal via the spin transfer torque (STT) effect[2,3]
We demonstrate dual manipulation of T ⊥ via external magnetic field and external bias which provides a new avenue to achieve both ‘reading’ and ‘writing’ processes of nonvolatile field-like spin torque magnetic random access memory (MRAM) (FLST-MRAM), which may require lower critical current densities for magnetization switching than conventional STT-MRAM
Junctions, T decays exponentially as the number of layers in the insulating and SF barriers increases with the same decay rate
Summary
Recent discoveries in the ferromagnet/insulator/ferromagnet (FM/I/FM) magnetic tunnel junctions (MTJs) have demonstrated that the relative orientation of the two FM electrodes can be either altered by an external magnetic field, i.e. the tunneling magnetoresistance (TMR) effect[1], or controlled by a spin-polarized current, i.e. the current-induced magnetization reversal via the spin transfer torque (STT) effect[2,3]. We demonstrate dual manipulation of T ⊥ via external magnetic field and external bias which provides a new avenue to achieve both ‘reading’ and ‘writing’ processes of nonvolatile field-like spin torque MRAM (FLST-MRAM), which may require lower critical current densities for magnetization switching than conventional STT-MRAM
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