Dielectric interfaces critical for metal–oxide–semiconductor electronic devices possess spin-coherent trap states that can behave as quantum sensors of small magnetic fields or, through spin noise, contribute to the spin decoherence of electronic quantum bits (qubits). The existence of small numbers of such traps can be electrically detected through spin-dependent recombination current; however, the interpretation of such measurements is only now possible after the publication of a general theory of the phenomena [Harmon et al. Appl. Phys. Lett. 123 251603 (2023)]. This article compares two electrical trap-spin measurement and identification techniques, electrically detected magnetic resonance and the recently observed near-zero field magnetoresistance, with Shockley–Read–Hall trap-assisted recombination current calculations. The bias dependence of these electrical effects provides direct evidence that, for the Si/SiO2 interface, spin mixing of the carriers producing the recombination current occurs via an effective semiclassical hyperfine interaction emanating from the bath of nuclear spins. The results can be generalized to describe the recombination current used as the sensing signal in all-electrical quantum magnetometers, as well as to provide quantitative descriptions of the spin-induced noise relevant for spin qubits near the Si/SiO2 interface.
Altermagnetism has recently emerged as a distinct magnetic order combining compensated magnetic moments with symmetry-driven spin splitting in momentum space, offering new opportunities for spintronic functionalities without net magnetization. Here, we investigate the manganese sulfides family as an experimentally accessible altermagnetic materials platform through a combined theoretical and experimental study. First-principles density functional theory calculations reveal that while MnS exhibits a conventional antiferromagnetic electronic structure without spin splitting, both MnS2 and Mn2S3 host pronounced altermagnetic spin splitting arising from their symmetry-inequivalent magnetic sublattices. Experimentally, manganese sulfide thin films are synthesized by sputtering, where high resolution transmission electron microscopy and x-ray photoelectron spectroscopy unambiguously confirm the existence of MnS2 at moderate deposition temperatures. Magnetic and electrical measurements further corroborate the theoretical predictions. Our results establish manganese sulfides as a chemically simple, thin-film-compatible materials family and provide practical growth constraints for investigating their altermagnetism, thereby advancing its experimental exploration and materials engineering.
The influence of a copper substitution in an MgO lattice and the nature of hole states surrounding the dopant are investigated using hybrid quantum mechanical/molecular mechanical calculations at the density functional theory level alongside new Electron Paramagnetic Resonance (EPR) spectroscopic data on a synthesized sample of the material. In calculations, the neutral Cu(II)–MgO system displays Jahn–Teller distortion around the copper center in both tetragonally elongated and compressed configurations, in line with previous computational and experimental findings. Subsequently, the behavior of an electron hole is investigated in Cu(II)–MgO, which has been previously unexamined prior to this work. For this charged system, it is clearly shown that in the ground state a hole will delocalize across all coordinated oxygens. Localization of a hole on an oxygen species is possible but is found to be higher in energy, and a hybrid functional with an increased fraction of Hartree–Fock exchange is necessary. Notably, the calculations show that oxidation of the copper species to Cu(III) is not possible. The spin Hamiltonian parameters for the monoatomic copper centers in bulk MgO for both the neutral and ionized systems are also calculated and compared to experimental values obtained by EPR spectroscopy on a polycrystalline Cu(II)–MgO sample. The computed spin Hamiltonian parameters are shown to be largely consistent with the experimental parameters, and the axial distortion in the directional parameters in the material confirms that the copper dopant causes tetragonal elongation in its bonding with neighboring oxygen atoms.
We report high-pressure Raman scattering measurements on ZnO nanowires up to ∼20 GPa, supported by density functional theory calculations. The wurtzite (B4) phase transforms to the cubic rock salt (B1) structure at ∼10 to 13 GPa, accompanied by the appearance of disorder-activated Raman modes. The pressure dependence of phonon modes in the nanowires is directly compared with theoretical predictions for both the B4 and B1 phases of bulk ZnO, providing a unified description of lattice dynamics across the phase transition and deeper insight into size- and dimensionality-related effects, a connection not systematically explored in previous studies. Upon decompression, the B1 phase persists metastable down to ∼0.8 GPa, revealing pronounced hysteresis and a substantially reduced reverse transition pressure. The recovered wurtzite phase exhibits broadened Raman features and frequency shifts, indicative of residual strain and defect accumulation. Linewidth analysis shows that most B1 modes exhibit comparable FWHM values during compression and decompression, implying similar phonon lifetimes and reversible lattice dynamics, with deviations attributed to disorder. Anomalies near ∼10 and ∼0.8 GPa are linked to lattice anharmonicity and phase reconstruction. Pressure coefficients and Grüneisen parameters agree with bulk trends, while deviations reflect size- and defect-related effects in the nanowires.
Photoelectrochemical water splitting has emerged as one of the most promising strategies for direct production of green hydrogen, an energy carrier with high energy density and zero carbon emissions. Among recent developments, halide perovskite semiconductors have attracted significant attention due to their outstanding optoelectronic properties, including strong light absorption, high charge carrier mobility, and tunable bandgaps. The integration of halide perovskites as light-absorbing layers in synergy with charge transport, protective, and catalytic layers into photoelectrode architectures has yielded promising scalability, high photocurrent densities, and extended operational stability. This review examines the role of each material that constitutes photoelectrodes based on halide perovskites and summarizes key evaluation parameters, namely photocurrent density, overpotential, and operational stability. In addition, a framework for conducting the electrochemical characterization of the devices is discussed, and key strategies commonly employed for selecting materials that reach high photocurrent densities and extended operational stability are outlined. Although performance metrics are extracted at thermodynamic potentials of oxygen (1.23 V) and hydrogen (0 V) evolution reactions, stability studies show that even small deviations in applied bias accelerate degradation processes, such as hydration, halide migration, and interfacial corrosion. As a result, current tests duration typically ranging from minutes to hundreds of hours remain as the main bottleneck, outweighing the already demonstrated high photocurrents and efficiencies. Key challenges include photocurrent retention, chemical and structural stability under prolonged operation, and the need for more robust transport layers and encapsulation strategies capable of mitigating degradation mechanisms induced by voltage, light, as well as water contact.
