Nanomaterials

Low magnetic damping and narrow ferromagnetic resonance (FMR) linewidth are essential for efficient spin-wave excitation in magnonic devices. We investigate how a combination of deposition techniques, interface engineering, and consequent thermal treatment affects magnetic losses in thin permalloy (Py, Ni₈₀Fe₂₀) films prepared by electron-beam evaporation and magnetron sputtering. Broadband vector network analyzer FMR, atomic force microscopy, and electromagnetic simulations were used to correlate linewidth, surface morphology, and spin-wave excitation. Comparable minimum linewidths were reached by both deposition routes: approximately 23 Oe at 4 GHz for the best electron-beam-evaporated film and approximately 21 Oe for a 20 nm TaN/Py/TaN structure. Electron-beam-evaporated films proved sensitive to substrate choice, surface preparation and—in the absence of plasma cleaning—deposition temperature, whereas the magnetic field applied during growth had only a weak effect. After magnetic annealing, however, only the TaN-encapsulated structure retained its narrow linewidth, while the uncapped films broadened substantially. Simulations further showed that linewidth reduction enhances the excitation efficiency and visibility of standing spin-wave modes. These results indicate that comparable losses are achievable through several process routes, whereas retaining them through thermal processing requires interface engineering—a distinction that matters for integrating Py films into magnonic and spintronic devices.

HfO₂-based ferroelectrics have extended a familiar CMOS high-κ dielectric into a materials platform for nonvolatile memory, low-power logic, and in-memory hardware. This review examines thickness engineering in hafnia, especially Hf_0.5Zr_0.5O₂ (HZO), through the state produced during fabrication, the voltage and time available for switching, and the signal retained during operation. Representative quantitative comparisons retain stack, anneal, electrical state, and endpoint definitions; they show that conditioning and drive voltage can change the apparent thickness trend substantially. Capacitor memory, FeFETs, tunnel junctions, negative-capacitance transistors, and computing devices are compared through architecture-specific read margins and failure criteria. The main unresolved challenge is to isolate thickness effects from coupled process and interface changes and establish reproducible, device-specific operating windows.

Efficient photo-Fenton catalysis requires the simultaneous optimization of light harvesting, photogenerated-charge utilization, and metal-mediated H₂O₂ activation. Herein, amorphous Cu-FeOOH clusters were assembled on oxygen-vacancy-rich Fe-doped BiOCl nanoflowers (Fe-BOCov) to construct a Cu-FeOOH/Fe-BOCov composite for efficient photo-Fenton catalysis. Oxygen-vacancy engineering and Cu-FeOOH coupling extended visible-light absorption and improved interfacial charge separation, as supported by the enhanced photocurrent response and reduced electrochemical impedance. Under AM 1.5G simulated solar irradiation, the optimized catalyst removed more than 90% of levofloxacin (LEV) within 10 min and exhibited an apparent pseudo-first-order rate constant of 0.271 min⁻¹. Radical-quenching and electron spin resonance measurements identify •OH and •O₂⁻ as the principal reactive species, with photogenerated holes also contributing. A mechanism is proposed in which electrons generated in oxygen-vacancy BiOCl migrate to Cu-FeOOH sites, facilitate Fe(III)/Fe(II) and Cu(II)/Cu(I) cycling, and accelerate H₂O₂ activation. This work demonstrates a defect-and-interface strategy for coupling solar-energy utilization with bimetallic Fenton chemistry.