Mehak Loyal

Van der Waals (vdW) heterostructures combining two‐dimensional (2D) ferromagnets and semiconducting transition‐metal dichalcogenides (TMDCs) offer highly promising opportunities for tailoring 2D magnetism through interfacial proximity effects, enabling unique physical phenomena inaccessible in 3D systems and achieving functionalities beyond conventional spintronics. However, current fabrication of vdW heterostructures still relies heavily on the manual stacking of exfoliated 2D flakes, leading to critical challenges in scalability, interfacial quality, thickness control and device integration. This work reports on the realization of all‐epitaxial, high‐quality Fe _{5− x} GeTe ₂ (FGT)/WSe ₂ heterostructures exhibiting perpendicular magnetic anisotropy (PMA) and room‐temperature ferromagnetism. The FGT/WSe ₂ system demonstrates temperature‐driven magnetic transitions, higher‐order PMA contributions and large anisotropic magnetoresistance, highlighting sublattice‐specific contributions to magnetic and transport properties. Notably, the FGT/WSe ₂ heterostructures display unconventional physical phenomena, including thickness‐ and temperature‐dependent sign reversal of exchange bias, a reversed thickness trend in the unconventional Hall effect, and a non‐monotonic PMA‐thickness dependence. These anomalies indicate pronounced interfacial contributions arising from proximity effects enhanced by epitaxial interface quality. Collectively, this study provides deep insights into the magnetic and transport properties of FGT/WSe ₂ vdW heterostructures, establishing a scalable platform for exploring emergent 2D physics and developing next‐generation 2D spintronic functionalities.

Recent predictions of orders of magnitude larger orbital current effects compared with spin currents have attracted considerable interest. However, orbital currents must first be converted into spin currents to interact with the static magnetization dominated by spin angular momentum in conventional magnets. By using a magnet dominated by orbital angular momentum (OAM), we demonstrate a 70-fold enhancement in orbital Hall magnetoresistance in cobalt II oxide/copper (CoO/Cu*), compared with spin Hall magnetoresistance in cobalt II oxide/platinum (CoO/Pt). This arises from interactions between dynamic OAM from surface-oxidized Cu* and static OAM in the antiferromagnetic insulator CoO. Our results show how by using OAM-dominated materials, we can harness the benefits of giant orbital currents that have not been possible using conventional spin-dominated magnets.

Rare-earth nitride (REN) pnictides are exciting materials due to their localized and strongly correlated 4f-electrons that lead to interesting magnetic properties useful for spintronic devices. Ytterbium nitride (YbN) is a unique rare-earth pnictide as it exhibits antiferromagnetic ground states, unlike most ferromagnetic RENs. Though the magnetic properties of YbN thin films have been studied before, the electronic, thermoelectric, and plasmonic properties of YbN are yet to be investigated. Here, we show coexisting high thermoelectric power factor and short-wavelength infrared plasmon polaritons in epitaxial YbN thin films deposited with the ultrahigh vacuum growth method. YbN thin films deposited on (001) MgO substrates exhibit epitaxial and good quality crystalline growth and exhibit a high thermoelectric power factor of ∼ 1.9 mW/mK2 at 750 K due to high electrical conductivity and a moderately high Seebeck coefficient. High carrier concentration also leads to a positive-to-negative dielectric permittivity transition in YbN at ∼1900–1950 nm, corresponding to the epsilon-near-zero plasmonic resonance. Low-temperature transport measurements revealed that dislocation and acoustic phonon scattering dominate electronic transport. Demonstration of coexisting high thermoelectric power factor and infrared plasmon polaritons marks important progress in designing YbN-based thermoelectric and plasmonic devices for future applications.