Discovery of robust topological hall signatures in the layered ferromagnet FePd₂Te₂ opens new routes for spintronic technologies

Introduction: The discovery of topological magnetic states has transformed modern condensed matter physics and spintronics. Magnetic skyrmions, chiral spin spirals, and noncoplanar spin textures generate emergent electromagnetic fields that produce exotic transport phenomena such as the topological Hall effect (THE). These nanoscale magnetic objects are particularly attractive because they can potentially be manipulated with extremely low energy consumption, making them ideal candidates for future memory and logic devices. In this context, van der Waals magnetic materials have emerged as an exceptional platform for exploring low-dimensional magnetism. Their atomically layered nature enables mechanical exfoliation, interface engineering, electrostatic tuning, and integration into heterostructures. Several layered magnets, including Fe₃GeTe₂ and Cr-based tellurides, have already demonstrated signatures of skyrmions and topological Hall responses.

However, despite remarkable progress, major challenges remain.  In micro‑devices the Hall response can be easily complicated by domain switching, domain‑wall pinning, or the superposition of multiple anomalous Hall components, all of which can mimic hump‑like features. Establishing robust, reproducible criteria to distinguish intrinsic THE‑type signals from such extrinsic effects remains a central challenge, especially, in van der Waals magnets where competing anisotropy and Zeeman energies can create narrow stability windows for complex spin states.

The Solution: The team performed systematic angle‑dependent magnetotransport on FPT Hall‑bar devices. The anomalous Hall amplitude does not follow a simple cos(θ) behavior, instead, it exhibits two plateaus near the in‑plane and out‑of‑plane field orientations, a hallmark of anisotropy‑driven spin reorientation in an easy‑plane ferromagnet. Within the spin‑reorientation window near the in‑plane geometry, an additional hump‑like Hall contribution develops. Quantitative global fitting using a two‑component (double‑tanh) anomalous Hall model fails to account for this feature self‑consistently across angles and temperatures, supporting the presence of an extra Hall component beyond conventional AHE. Temperature sweeps at the optimal angle reveal a distinct thermal pocket where the hump amplitude is maximized (~100 K).

Why it Matters: A key discriminator is robustness. The hump‑like Hall anomaly shows a reproducible angle–temperature evolution in both ~100 nm and ~450 nm flakes, despite the several‑fold change in thickness. Within an emergent‑field framework, the extracted THE amplitude yields nanoscale characteristic length scales (roughly 17–44 nm, depending on temperature), comparable to values reported in established chiral‑magnet platforms. Together, these results position FPT as a promising van der Waals platform for emergent topological transport that is not restricted to the ultrathin limit.

What’s Next: Future work will benefit from combining transport with real‑space magnetic imaging (e.g., Magnetic Force Microscopy (MFM) or Lorentz Transmission Electron Microscopy (LTEM)) to directly resolve the microscopic texture responsible for the emergent Hall signal. In parallel, systematic thickness, strain, and interface engineering in encapsulated devices or heterostructures could tune the spin‑reorientation thresholds and map out the full phase diagram of the topological Hall regime.

Reference: Jinjin Liu, Zherui Yang, Liu Yang, Baowen Li, Yanran Liu, Zhiwei Wang, Qiong Wu, Dongchen Qi, Xiao Renshaw Wang. Signature of topological Hall effect in layered FePd2Te2 ferromagnet[J]. Materials Futures, 2026, 5(3): 035303. DOI: 10.1088/2752-5724/ae55ba

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