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Researchers have created magnetic tunnel junctions by stacking two layers of La2/3Sr1/3MnO3, a ferromagnetic metal oxide, at twisted angles. The van der Waals gap between the layers acts as a tunnel barrier, enabling tunneling magnetoresistance (TMR) and tunneling anisotropic magnetoresistance (TAMR) effects that depend on the magnetic orientation of each layer. This demonstrates that electron spin and momentum are preserved across the junction, opening possibilities for quantum devices using strongly correlated oxide materials.
Why it matters
This technique could enable a new class of tunable spintronic devices that combine the unique magnetic and electronic properties of transition metal oxides with the flexibility of twisted-layer engineering. The ability to control quantum tunneling through angle adjustment may lead to more efficient memory storage devices and advanced quantum computing components.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: 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.
Source: Magnetic tunnel junctions of twisted La2/3Sr1/3MnO3 freestanding bilayers