Designer enhanced magnon transport in epitaxial, multiferroic heterostructures grown by molecular-beam epitaxy

Bismuth ferrite (BFO) is a room temperature magnetoelectric multiferroic with antiferromagnetic order and a large spontaneous polarization. In recent years, it has gained interest in the spintronics community for its use in non-volatile logic-in-memory devices. However, efficiently controlling the magnons in this material remains a challenge. Using molecular-beam epitaxy, we can precisely control the thickness and quality of each layer allowing for the creation of designer magnon transport. For this work, we grew samples of REFeO3/BiFeO3/REFeO3 (RE = rare earth elements such as La, Dy) and observed highly efficient magnon transport in an all-antiferromagnetic system that can be controlled electrically due to the coupling of the ferroelectric and antiferromagnetic ordering in BiFeO3. Leveraging spin-orbit-driven spin-charge transduction, we demonstrate that this material architecture permits magnon confinement in ultrathin antiferromagnets, enhancing the output voltage generated by magnon transport by several orders of magnitude, which provides a pathway to enable magnetoelectric memory and logic functionalities. Additionally, its non-volatility enables ultralow-power logic-in-memory processing, where magnonic devices can be efficiently reconfigured via electrically controlled magnon spin currents within magnetoelectric channels. Notably, by changing the thickness and rare earth elements of the REFeO3 layers can modulate the enhancement of the spin transport.