Strongly Bias‐Dependent Tunnel Magnetoresistance in Manganite Spin Filter Tunnel Junctions

Abstract

A highly unconventional bias-dependent tunnel magnetoresistance (TMR) response is observed in Sm0.75 Sr0.25 MnO3 -based nanopillar spin filter tunnel junctions (SFTJs) with two different behaviors in two different thickness regimes of the barrier layer. Thinner barrier devices exhibit conventional SFTJ behaviors; however, for larger barrier thicknesses, the TMR-bias dependence is more complex and reverses sign at higher bias.

Turning antiferromagnetic Sm0.34Sr0.66MnO3 into a 140 K ferromagnet using a nanocomposite strain tuning approach

“…M vs. T plots show ferromagnetism with a T C of 140 K for the nanocomposite film. We note that in the literature the highest T C value in the ferromagnetic insulating (FMI) Sr-doped SmMnO 3 system is 100 K 22 which is for the optimally doped (25% Sr doped) composition, and so the T C of the SSMO phase formed in our nanocomposite films is 40 K higher than for any FMI Sr-doped SmMnO 3 phase. In addition, the T C of our nanocomposite films is 10 K higher than for the ferromagnetic metal (FMM), Sr-doped SmMnO 3 (48% Sr).…”

“…20 Recently, spin filter tunnel junctions based on SSMO were fabricated into devices, 21 giving 75% spin polarization. However, the junctions operated mainly at a low temperature of 5 K. 22 Thus despite the promising bulk properties, in strained films wide deviations in the ferromagnetic properties result. [23][24][25][26][27][28] Indeed, the physical properties of SSMO, of low band width, have great sensitivity to both strain and composition.…”

Interface-Induced Enhancement of Ferromagnetism in Insulating LaMnO3 Ultrathin Films

“…With the rapid development of perovskite-based spintronics, perovskite FMIs have recently become a natural choice because of their chemical and structural compatibility with other functional perovskites . However, only a few perovskites have been known as FMIs, and their performance in spintronics is not satisfactory so far. ,− Taking into account the scarcity, new perovskite FMIs with robust ferromagnetism (FM) and high Curie temperature are in strong demand. In addition, the surfaces and interfaces of FMIs are also critical, as the interface effect is generally responsible for the emergence of a nonferromagnetic dead layer, which is thought to be inimical to the device applications .…”

Realizing Room‐Temperature Resonant Tunnel Magnetoresistance in Cr/Fe/MgAl2O4 Quasi‐Quantum Well Structures

“…The magnetic tunnel junctions (MTJs) consisting of ferromagnetic electrodes and an oxide barrier are widely investigated for the improvement or manipulation of TMR characteristics. [3][4][5][6][7][8][9] One of the remarkable transport properties found in the MTJs is interplay of TMR effect and resonant tunneling through quantum well (QW) states, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] which can be realized by double-barrier structures or simply by metallic stacking structures with a symmetry-dependent band structure. For the ultrathin-Fe/oxide with a (001) crystallographic orientation structure grown on a Cr buffer layer, spin-dependent QW states are formed for the Δ 1↑ symmetry electronic states in Fe, in which the "quasi" QW potential arises from the band mismatch between Cr Δ 1 and Fe Δ 1↑ .…”