Magnetic tunnel junctions of twisted La2/3Sr1/3MnO3 freestanding bilayers
Transition metal oxides (TMOs) host a variety of emergent spintronic or multiferroic functionalities owing to the intricate interplay between lattice, orbital, charge, and spin degrees of freedom. Recent advances in epitaxial lift-off and dry transfer techniques using water-soluble sacrificial layers enables stacking and twisting of freestanding membranes of such strongly correlated oxides, providing even richer physical properties and functionalities. To date, the twisted junctions of TMOs have been mainly investigated in insulators, focusing on their structural and dielectric properties. Here, we demonstrate that the twisted bilayer membranes of La2/3Sr1/3MnO3, a prototypical half-metallic ferromagnetic metal TMO, offer a magnetic tunnel junction (MTJ) with their van der Waals (vdW) gap acting as a tunnel barrier. The twisted junctions of La2/3Sr1/3MnO3 exhibit tunnelling magnetoresistance (TMR) effect with respect to relative orientation of magnetizations of top and bottom membranes. In addition, high-field magnetoresistance shows uniaxial anisotropy, which can be assigned to tunnelling anisotropic magnetoresistance (TAMR) effect reflecting rhombohedral distortion of fully-relaxed La2/3Sr1/3MnO3. The demonstration of TMR and TAMR effects suggests that spin and in-plane momentum degrees of freedom of 3d electrons are conserved across the twisted junctions of TMOs, opening a new avenue for realizing strongly correlated twistronics utilizing electron coherence through tunnelling processes.