Improved tunneling magnetoresistance at low temperature in manganite junctions grown by molecular beam epitaxy

TL;DR

This study demonstrates a significant low-temperature tunneling magnetoresistance in manganite junctions grown by molecular beam epitaxy, revealing high spin polarization and biaxial anisotropy, advancing spintronic device potential.

Contribution

It reports the first observation of extremely high TMR with biaxial anisotropy in manganite junctions grown by molecular beam epitaxy, challenging the need for uniaxial anisotropy.

Findings

TMR reaches ~1900% at 4K.

TMR exhibits 4-fold symmetry aligned with crystalline axes.

Interfacial spin polarization exceeds 95%.

Abstract

We report resistance versus magnetic field measurements for a La0.65Sr0.35MnO3/SrTiO3/La0.65Sr0.35MnO3 tunnel junction grown by molecular-beam epitaxy, that show a large field window of extremely high tunneling magnetoresistance (TMR) at low temperature. Scanning the in-plane applied field orientation through 360^/circ, the TMR shows 4-fold symmetry, i.e. biaxial anisotropy, aligned with the crystalline axes but not the junction geometrical long axis. The TMR reaches ~ 1900% at 4K, corresponding to an interfacial spin polarization of > 95% assuming identical interfaces. These results show that uniaxial anisotropy is not necessary for large TMR, and lay the groundwork for future improvements in TMR in manganite junctions.