Abstract Magnetism induced by the proximity effects of chiral molecules is a physical phenomenon that can be demonstrated with molecular layers as thin as 1 nm deposited on thin films of conventional ferromagnets. Although the chiral-induced spin selectivity effect has been widely explored in the context of spintronic applications involving charge transport through chiral molecules, due to its capacity to generate high spin polarizations at room temperature, the accompanying process of induced magnetization without applied current likewise presents opportunities for exploitation. In this work, we demonstrate that, unlike conventional ferromagnets, where the induced magnetization aligns with the chiral axis of the polymer, the CISS effect in half-metallic ferromagnets (La0.67Sr0.33MnO3) favors a quasi-perpendicular magnetization configuration. This preference for quasi-perpendicular magnetization is caused by the formation of a thermally driven steady state, which, due to different transport probabilities into the molecule, results in a modification of the domain-wall energy landscape. These results provide insight into the chiral-induced spin selectivity effect without net currents and also clarify mechanism for controlling magnetization within half-metallic thin films for spintronic devices.
Abstract Reliable pH sensing in liquid environments underpins applications in energy storage, biosensing, and process monitoring, yet conventional graphene-based electrical devices introduce ohmic contacts, encapsulation layers, and electrochemical artifacts that can obscure intrinsic behavior. These approaches also fail to capture the strong spatial variability of commercial CVD graphene. Here, we present a fully contactless methodology for quantifying pH-dependent conductivity of large-area CVD graphene using through-substrate reflection terahertz time-domain spectroscopy (THz-TDS). A customized liquid cell with a THz transparent window preserves unrestricted access to the graphene–electrolyte interface while enabling centimeter-scale conductivity mapping and in-operando single-point monitoring during sequential pH modulation. By integrating spatially registered Raman mapping with automated quality-metric filtering, we extract statistically robust trends across thousands of pixels rather than isolated device regions. We show that pristine monolayer graphene exhibits the highest baseline conductivity and strongest pH sensitivity, whereas O2-plasma-introduced defects systematically suppress both. This scalable, remote, and inert probing approach establishes THz-TDS as a powerful platform for high-throughput characterization and robust liquid-phase sensing in thin films and 2D systems.
Spin-charge interconversion provides the essential link between spin information and electrical signals in spintronic devices. In spin-orbit coupled systems, spin-charge interconversion can contain multiple components associated with different spin-polarization directions, reflecting the underlying spin texture. Tuning this spin texture therefore provides a way to control not only the magnitude of spin-charge interconversion, but also the balance among its different components. Graphene-based van der Waals heterostructures provide an attractive platform for this purpose because interfacial spin-orbit coupling can host multiple spin-charge interconversion channels that couple to different spin-polarization directions. Here, we demonstrate electric-field control of spin texture in a dual-gated HfS_2/graphene van der Waals heterostructure, where independent control of carrier density and vertical electric field allows us to disentangle electrostatic doping from electric field-induced spin-orbit effects. Nonlocal spin precession measurements show that near zero vertical electric field, spin-charge interconversion is dominated by a spin Hall component with out-of-plane spins. Increasing the vertical electric field enhances additional in-plane spin components with Rashba-Edelstein-like character, including both parallel and perpendicular to the charge current contributions. These results provide experimental evidence that a vertical electric field can reconfigure the effective spin texture and control the corresponding spin-charge interconversion components, demonstrating electrical tunability of spin-orbit functionalities.
Abstract Improving the sensitivity of two-dimensional semiconductor phototransistors requires increasing photocurrent while minimizing noise. However, conventional doping approaches often place charged dopants in or near atomically thin channels, introducing charge scattering, trap states, and noise that limit the signal-to-noise ratio. Here, we address this signal-noise trade-off in WSe2 phototransistors by using photoinduced charge trapping in patterned hBN to implement contact-selective remote doping. Under illumination with a negative gate voltage, trapped holes in hBN electrostatically n-dope WSe2 while remaining spatially separated from the transport channel. Patterned hBN confines the doping to selected regions, allowing the WSe2 near the metal electrodes to be remotely doped while leaving the channel undoped. This remote contact doping simultaneously suppressed the device noise by approximately 100–fold, reduced the effective density of electrically active traps by approximately 100–fold, and lowered the activation energy by 30–80 meV, indicating improved contact quality and more efficient carrier injection. As a result, the contact-doped phototransistors simultaneously exhibit enhanced responsivity of 99.7 A/W and a specific detectivity of 2.26 × 1011 Jones. These results establish optically programmed remote contact doping as a phototransistor-compatible contact-engineering approach to overcome the signal–noise trade-off in 2D phototransistors.
Abstract Porous single-layer graphene (PG) offers an ideal platform for molecular-sieving membranes due to its atomically thin inorganic lattice and its ability to incorporate molecularly selective pores. However, the use of PG for high-temperature gas separation remains limited by the lack of a mechanically reinforcing film (MRF) that enables crack-free transfer onto porous supports and stable operation under pressurization. Here, we introduce a fluorinated porous organic polymer (FPOP) that provides the mechanical and thermal robustness needed to operate PG membranes at high temperature. The FPOP layer is deposited directly on PG from a molecular precursor solution. Upon drying and thermal annealing, it develops into a continuous cross-linked film that conforms to PG, maintains strong adhesion, and helps to avoid crack formation during the transfer of PG to a macroporous support. The FPOP film exhibits a quasi-ordered structure, forms an interface with graphene, and remains stable under pressurized conditions up to 350 °C. FPOP-supported PG membranes exhibit selective gas transport at elevated temperature (350 °C) and maintain their performance during extended mixed-gas operation. The membranes retain selective transport after humid/oxidative exposure and ambient storage. Importantly, the porous FPOP can regulate transport through enlarged nonselective graphene defects, thereby improving the selectivity of PG membranes. Overall, we demonstrate FPOP as a thermally stable MRF platform that enables crack-free PG transfer, high-temperature operation, and regulation of nonselective transport pathways.
