Post by Aditya Kumar

Excited to share that our perspective article is now published in Newton (Cell Press)! When I started working with van der Waals magnetic materials, I did expect problems in experimentation and implementation but not in materials. These are single-crystal materials with atomically flat interfaces; they should be the textbook case for exchange bias. The ideal models should just work. But sample after sample, they didn't. Thickness dependences deviated from predictions. Signals showed up where the theory said there should be none. I kept looking for problems in our experimental setup and measurement protocols, not in the materials themselves. It took three publications across different van der Waals systems before the picture became clear: the experiments weren't failing. They spoke the truth. In a conventional thin-film heterostructure, a 5 nm layer on top of another 5 nm layer means two materials and one interface. In van der Waals materials, that is not the case. Each monolayer is held together by weak forces and weak interlayer exchange, so a stack that appears as two layers actually contains an interface between every pair of monolayers. A single flake is not a single system. And that changes everything about how magnetic coupling works. In this perspective, together with Aravind Puthirath Balan, Sadeed Hameed, Xinran Wang, and my supervisor Prof. Mathias Kläui, we show that these anomalies are not quirks of individual samples. They are intrinsic to vdW materials. What initially looked like scattered failures now reveals a coherent picture: these materials offer fundamentally different opportunities for spintronic devices, not despite their complexities, but because of them. Herbert Kroemer, who won the Nobel Prize for semiconductor heterostructures, once said: "The interface is the device." In van der Waals materials, every layer boundary is an interface. That is not a complication; it is an opportunity we are only beginning to understand. The full article is open access: https://lnkd.in/d2ZzUsNk #Spintronics #VanDerWaals #ExchangeBias #2DMaterials #MaterialsScience #Newton #CellPress