MagicTune: Enabling large tunnel magnetoresistance at room temperature in scalable epitaxial van der Waals magnet heterostructures

The emergence of atomically thin two-dimensional (2D) materials and their van der Waals (vdW) heterostructures has sparked significant scientific interest due to their unprecedented electronic and magnetic properties for next-generation technologies. Among these, 2D magnets hold particular promise for revolutionizing magnetic sensors and spintronic devices — especially magnetic tunnel junctions (MTJs), which exploit tunneling magnetoresistance (TMR) for ultra-high magnetic field sensitivity at room temperature. Gepris

However, conventional materials face major challenges in achieving reliable and tunable TMR devices. Recent advances with 2D magnets have produced large TMR values, but these results are typically limited to cryogenic temperatures and systems based on mechanically exfoliated flakes. Scalable synthesis of 2D magnets and fabrication of MTJs with multiple layers separated by a tunnel barrier remain formidable tasks. In addition, the influence of coherent, spin-polarized electron tunneling across vdW tunnel barriers on TMR performance is not yet understood. Gepris

The MagicTune project aims to overcome these challenges by developing methods to control spin-polarized tunneling in 2D MTJs through precise tuning of the interlayer twist angle and electrical gate voltage. By doing so, the project seeks to achieve large, tunable TMR effects at room temperature. Gepris

To this end, scalable growth processes for high-quality vdW magnetic heterostructures with high Curie temperatures (T₍C₎ ≥ 350 K) and strong perpendicular magnetic anisotropy (PMA) will be developed using molecular beam epitaxy and related techniques. The project will maximize tunnel spin polarization in MTJs by exploiting momentum-conserving electron tunneling across atomically sharp vdW barriers. Robust TMR device performance at room temperature, with TMR ratios above 100 %, will be demonstrated using epitaxial vdW magnetic heterostructures. Gepris

MagicTune brings together expertise in epitaxial growth and characterization, synthesis of vdW templates, TMR device design, twistronics, spin and quantum transport measurements, and nanofabrication of all-2D nanodevices. Successful outcomes from this project are expected to deliver breakthroughs in TMR functionality and enable high-performance, compact, and energy-efficient technologies based on 2D heterostructures.

Funded by the Deutsche Forschungsgemeinschaft (DFG) - Project number 533948427