We report on heat capacity measurements on thin gold films deposited on Si before and after chemisorption of chiral and achiral molecular monolayers, performed by applying Joule heating and time-resolved thermometry. Our results reveal modifications in heat capacity with a distinct dependence on molecular chirality and organizational structure: Ordered homochiral monolayers increase the Debye temperature, while disordered monolayers, whether chiral or achiral, significantly decrease it. In contrast, ordered racemic monolayers induce no notable change, suggesting a critical role of net chiral symmetry in altering the phonon spectrum. These findings indicate that the vibrational properties of a molecularly treated metal are governed not simply by molecular identity, but rather by the interplay between chirality and spatial organization, pointing to a chiral-specific coupling mechanism at the interface.

The influence of chiral molecular potentials on phase-coherent transport in superconducting Josephson junctions is investigated. Within a Bogoliubov-de Gennes tight-binding framework, an SNS junction functionalized by adsorbed chiral molecules is modeled, where electrostatic gradients generated by the molecules induce spin-orbit coupling in the normal region. The equilibrium charge current-phase relation is found to remain largely insensitive to molecular chirality in symmetric, zero-field configurations. In contrast, the spin supercurrent exhibits a pronounced chirality-dependent response, with opposite enantiomers producing distinct and anisotropic spin-polarized Josephson currents. The resulting handedness contrast can be enhanced through control parameters such as molecular orientation and the strength of the induced spin-orbit coupling. The temperature dependence of these currents further shows that the chirality-dependent signatures persist across a range of temperatures well below the superconducting critical temperature. These results establish Josephson interferometry as a phase-sensitive and accessible platform for detecting molecular chirality and highlight spin-polarized superconducting transport as a promising route toward integrating chiral molecular functionality into superconducting spintronic devices.

Abstract Mapping edge supercurrents in thin superconducting films and resolving the Meissner and vortex contributions provide important insights into the nature of type II two-dimensional superconductors. Here, we perform tunneling spectroscopy measurements on thin exfoliated NbSe2 flakes to probe Doppler shifts of the quasiparticle density of states and extract the current density at the flake edge with a resolution of 5–10 μA/μm. We observe a distinct hysteretic response of the tunneling spectra under small out-of-plane magnetic fields, allowing a deconvolution of the Meissner and vortex current contributions. The isolated contributions of Meissner currents to the Doppler shift are corroborated using a numerical solution of the London equations. Our results demonstrate that tunneling devices are highly effective for monitoring non-equilibrium and dynamical effects in thin superconducting films.

The nature of superconductivity in the transition metal dichalcogenide family, particularly 2H-NbSe2 and 2H-TaS2 in the ultrathin limit, is not fully understood. While tunneling measurements apparently show a single superconducting gap, its detailed shape cannot be reproduced by simple single-band theories of superconductivity. In this work, we present tunneling data into thin exfoliated samples of both materials and show excellent agreement with the McMillan two-band model of superconductivity when the scattering parameters are large with respect to the superconducting gaps, even when only a single gap is apparent. We propose that in thin samples, these highly cross-scattering gaps reside on the Gamma and K Fermi surfaces derived from the transition metal atoms. Additionally, we quantitatively analyze pair breaking induced by magnetic field, and find that it is also well described by the two-band McMillan theory. Our results thus suggest that in its bulk thickness, 2H-NbSe2 is likely a three-band superconductor.

The process of copper oxidation has been thoroughly studied for many years, yielding a significant understanding of its kinetics and chemistry. However, the possible roles of surface spin polarization in important issues such as oxidation rates have not been widely explored despite the triplet nature of molecular oxygen. Here, we investigate the spin-dependent oxidation of copper films by triplet O2, exploiting engineered ferromagnetic substrates to impose controlled surface spin polarization. Three sample architectures that enable comparison between spin-polarized and nonpolarized surfaces were implemented to enable direct comparison between regions of varying spin polarization on the same sample. Combining various surface-sensitive techniques, including atomic force microscopy, Kelvin probe force microscopy, ellipsometry, and magneto-optical Kerr effect, we followed oxide growth kinetics and electronic property changes over time scales from minutes to weeks. Our results demonstrate that spin-polarized surfaces exhibit a significant acceleration in copper oxide formation compared with less polarized regions. The difference appears to be driven by a preference toward the formation of cupric oxide (CuO), the second oxidation state of copper, over cuprous oxide (Cu2O), the first oxidation state. We suggest that the results are related to the different magnetic properties of each oxide. Our data also reveal that the CuO oxidation phase propagates from the Cu film edges toward the center of the sample. These findings provide direct evidence of the surface-spin influence on metal oxidation kinetics and support the notion that spin polarization can induce a lower activation energy barrier for electron transfer between metal to triplet O2. Beyond advancing the fundamental understanding of corrosion chemistry, this spin-dependent control of surface reactivity opens potential avenues for tailored catalyst design, spintronic device stability, and corrosion mitigation strategies.

Multinary metal oxide photoelectrodes remain fundamentally limited by poor charge transport despite theoretical promise for solar fuel production. α-SnWO4 exemplifies this challenge: while density functional theory predicts highly anisotropic charge transport with orientation-dependent band-edge positions, synthetic barriers to achieving phase-pure films with controlled crystallographic orientation have prevented its exploitation. Here, we demonstrate that rapid thermal processing (RTP) of pulsed-laser-deposited films overcomes these synthetic limitations, creating percolation networks of co-oriented grains. Multiscale characterization reveals that aligned crystallographic orientations produce well-aligned band edges, lowering contact potential difference by 0.35 eV and enhancing the local conductivity by more than 2 orders of magnitude compared to furnace heating (FH). These results directly correlate enhanced transport properties with previously reported improved photoelectrochemical performance of the RTP-treated films compared to those treated by FH and suggest a microscopic mechanism for this improvement. Our findings establish that controlling grain orientation connectivity, not simply grain size, provides a scalable pathway for exploiting anisotropic transport in multinary metal oxide photoelectrodes, directly linking the microstructure to the enhanced charge transport required for practical solar fuel devices.

Van der Waals (vdW) ferromagnets have garnered extensive attention thanks to their layered structures and the possibility of thinning them down to just a few atomic layers. This review discusses the emergent nanoscale magnetism in CrGeTe₃ (CGT), a 2-D vdW ferromagnet, focusing on its nanoscale properties and potential spintronic applications. We report on local magnetic probe techniques showing that thin CGT films exhibit spontaneous global magnetization at zero field, while thicker flakes display a hard ferromagnetic response only at their edges. We then focus on magnetic edge states in CGT thin films and their potential applications, where direct amorphization of CGT results in magnetic edges similar to those in cleaved films. By fabricating nanopatterned magnetic arrays, it has been demonstrated that tunable magnetic states emerge with anomalous coercivity. Moreover, we present the potential to realize artificial spin-ice configurations through antiferromagnetic dipolar coupling. The review delves into CGT heterostructures, which have demonstrated an anomalous Hall effect, expanding the scope of phenomena accessible in thin magnets. Finally, we discuss observation of magnetic bubbles and skyrmions, which offer additional opportunities for exploring chiral domain structures. The studies of CGT underscore the promise of fundamental investigations into 2-D magnetism while opening new pathways for spintronic applications based on nanoscale magnetic effects and frustration phenomena.

Technological advancements drive the demand for smart, flexible, and sustainable devices capable of integration into daily life. Pressure sensors, particularly those utilizing halide perovskites, face key challenges in sensitivity, stability, and integration with soft systems. This study focuses on the investigation of quasi-two-dimensional (2D) perovskite pressure sensors, where the perovskite is embedded within a polyvinylidene fluoride (PVDF) polymer matrix and protected by a polydimethylsiloxane (PDMS) polymer layer. The improvement in the performance of the pressure sensors is achieved through the optimization of the solvent composition, perovskite : PVDF ratio, and thickness of the PDMS layer, with a deep understanding of the morphological structure's influence on piezoelectric properties. Our perovskite layer achieves a high piezoelectric coefficient (d33) of 31.26 pm V-1, surpassing previously reported values for halide perovskites. Unlike previous studies, we systematically investigate the correlation between the PDMS thickness and the piezoelectric response, identifying a critical thickness threshold (similar to 23 mu m) beyond which sensing is suppressed. The devices demonstrate pressure sensitivity in the absence of any external power source and maintain reliable performance for 1000 cycles and up to 60 days under ambient conditions. Successful integration of the sensors into soft robotic grippers while also demonstrating sensitivity to various weights highlights their potential for application in fields such as soft robotics and healthcare.

The combination of a superconductor with a magnetically inhomogeneous material has been established as an efficient mechanism for the generation of long-ranged spin-polarized (spin-triplet) Cooper pairs. Evidence for this mechanism, however, has been established based on studies done on three-dimensional systems, where the strong bonds existing at the interface between the superconductor and the magnetic material should in principle enhance proximity effects and strengthen any electronic correlations. Here, we fabricate devices based on van der Waals stacks of flakes of the two-dimensional superconductor $NbS_2$ combined with flakes of $Cr_{1/3}NbS_2$, which has a built-in magnetic inhomogeneity due to its helimagnetic spin texture at low temperatures. We find that the critical temperature of these vdW bilayers is strongly dependent on the magnetic state of $Cr_{1/3}NbS_2$, whose degree of magnetic inhomogeneity can be controlled via an applied magnetic field. Our results demonstrate evidence for the generation of long-ranged spin-triplet pairs across the $Cr_{1/3}NbS_2$/$NbS_2$ vdW interface.

In metallic transition metal dichalcogenides (TMDs), which remain superconducting down to single-layer thickness, the critical temperature Tc decreases for Nb-based, and increases for Ta-based materials. This contradicting trend is puzzling, impeding the development of a unified theory. Here we study the thickness-evolution of superconducting tunneling spectra in TaS2 heterostructures. The upper critical field Hc2 is strongly enhanced towards the single-layer limit - following H c 2 ∝ T c 2 . The same ratio holds for the entire family of intrinsically metallic 2H-TMDs, covering 4 orders of magnitude in Hc2. Using Gor'kov's theory, we calculate the suppression of Tc by the competing charge density wave (CDW) order, which affects the quasiparticle density of states and the resulting Tc and Hc2. The latter is found to be universally enhanced by two orders of magnitude. Our results substantiate CDW as the key determinant factor limiting Tc across the TMD family.

Nano-patterned magnetic materials have opened new venues on the investigation of strongly correlated phenomena including artificial spin-ice systems, geometric frustration, magnetic monopoles, for technologically important applications such as reconfigurable ferromagnetism. With the advent of atomically thin two-dimensional (2D) van der Waals (vdW) magnets a pertinent question is whether such compounds could make their way into this realm where interactions can be tailored so that unconventional states of matter could be assessed. Here we show that square islands of CrGeTe3 vdW ferromagnets distributed in a grid manifest antiferromagnetic correlations, essential to enable frustration resulting in an artificial spin-ice. By using a combination of SQUID-on-tip microscopy, focused ion beam lithography, and atomistic spin dynamic simulations, we show that pristine, isolated CGT flakes as small as 150*150*60 nm3 have tunable dipole-dipole interactions, which can be precisely controlled by their lateral spacing. There is a crossover between non-interacting islands and significant inter-island anticorrelation depending how they are spatially distributed allowing the creation of complex magnetic patterns not observable at the isolated flakes. Our findings suggest that the cross-talk between the nano-patterned magnets can be explored in the generation of even more complex spin configurations where exotic interactions may be manipulated in an unprecedent way.

The coercivity of single-domain magnetic nanoparticles typically decreases with the nanoparticle size and reaches zero when thermal fluctuations overcome the magnetic anisotropy. Here, we used SQUID-on-tip microscopy to investigate the coercivity of square-shaped CrGeTe3 nanoislands with a wide range of sizes and width-to-thickness aspect ratios. The results reveal an anomalous size-dependent coercivity, with smaller islands exhibiting higher coercivity. The nonconventional scaling of the coercivity in CrGeTe3 nanoislands was found to be inversely proportional to the island width and thickness (1/wd). This scaling implies that the nanoisland magnetic anisotropy is proportional to the perimeter rather than the volume, suggesting a magnetic edge state. In addition, we observe that 1600 nm wide islands display multi-domain structures with zero net remnant field, corresponding to the magnetic properties of pristine CrGeTe3 flakes. Our findings highlight the significant influence of edge states on the magnetic properties of CrGeTe3 and deepen our understanding of low-dimensional magnetic systems.

We investigate the voltage–current characteristics of a superconductor–insulator–ferromagnet heterostructure, where the insulating layer contains pinhole-defects. The superconducting layer exhibits multiple voltage jumps that are hysteretic with the current sweep direction. This characteristic of the resistive state is due to pinholes that induce local, distinct, coupling regions between the superconducting and ferromagnetic layers which may generate phase-slip lines or vortex channeling. These findings point to a magnetically driven design of a superconductor memristor. Concomitantly, the junctions display both absolute and differential negative resistances below the superconducting critical temperature and current. This anomalous behavior is analyzed using a circuit approach and is attributed to current passing through pinholes within the insulating layer. These two unique effects, which stem from the special topology of the pinholes-governed interface can be applied in superconductor-based switches and memory devices.

Chiral imprinting is demonstrated in metals, semiconductors, and oxides. In these cases, the mixing of chiral molecules with the studied material changes the structure of the hybrid system, resulting in new physical properties. In this work, chirality is imprinted on lead (Pb) that is a conventional singlet s‐wave superconductor. The hybrid material exhibits an increase in the critical field ( H C ) and a wider temperature phase transition under in‐plane magnetic fields. These results demonstrate a method for locally altering the magnetic‐response properties of conventional superconductors.

In‐gap states and their effect on recombination rates in quasi‐2D lead–iodide‐based perovskites, intercalated with various spacer molecules, are studied using a combination of scanning tunneling spectroscopy and temperature‐dependent photoconductivity measurements. The results are further analyzed by a Shockley–Read–Hall model. Indications for shallow in‐gap states, positioned at about 0.15–0.2 eV below the bottom of the conduction band, are found. These states are identified as dominating the recombination route of photogenerated carriers in these systems, with a relatively large capture coefficient of about 10 −5 –10 −6 cm 3 s −1 at room temperature. First‐principles calculations based on density functional theory imply that these states are not an intrinsic effect of the inclusion of the spacer molecules, but rather one that arises from chemical defect formation or structural deformation of the perovskite layers. The results suggest that further improvement of the performance of solar cells that are based on quasi‐2D perovskites requires, along with enhancing carrier mobility, efforts to suppress the concentration of these detrimental defect states.

The synthesis of two-dimensional van der Waals magnets has paved the way for both technological applications and fundamental research on magnetism confined to ultra-small length scales. Edge magnetic moments in ferromagnets are expected to be less magnetized than in the sample interior because of the reduced amount of neighboring ferromagnetic spins at the sample edge. We recently demonstrated that CrGeTe3 (CGT) flakes thinner than 10 nm are hard ferromagnets; i.e., they exhibit an open hysteresis loop. In contrast, thicker flakes exhibit zero net remnant field in the interior, with hard ferromagnetism present only at the cleaved edges. This experimental observation suggests that a nontrivial interaction exists between the sample edge and the interior. Here, we demonstrate that artificial edges fabricated by focus ion beam etching also display hard ferromagnetism. This enables us to write magnetic nanowires in CGT directly and use this method to characterize the magnetic interaction between the interior and edge. The results indicate that the interior saturation and depolarization fields depend on the lateral dimensions of the sample. Most notably, the interior region between the edges of a sample narrower than 300 nm becomes a hard ferromagnet, suggesting an enhancement of the magnetic exchange induced by the proximity of the edges. Last, we find that the CGT regions amorphized by the gallium beam are nonmagnetic, which introduces a novel method to tune the local magnetic properties of CGT films, potentially enabling integration into spintronic devices.

The interplay between magnetism and superconductivity can lead to unconventional proximity and Josephson effects. A related phenomenon that has recently attracted considerable attention is the superconducting diode effect, in which a non-reciprocal critical current emerges. Although superconducting diodes based on superconducting/ferromagnetic (S/F) bilayers were demonstrated more than a decade ago, the precise underlying mechanism remains unclear. While not formally linked to this effect, the Fulde-Ferrell-Larkin-Ovchinikov (FFLO) state is a plausible mechanism, due to the 2-fold rotational symmetry breaking caused by the finite center-of-mass-momentum of the Cooper pairs. Here, we directly observe, for the first time, a tunable superconducting vortex diode in Nb/EuS (S/F) bilayers. Based on our nanoscale SQUID-on-tip (SOT) microscope and supported by in-situ transport measurements, we propose a theoretical model that captures our key results. Thus, we determine the origin for the vortex diode effect, which builds a foundation for new device concepts.

Recently, electron transport along chiral molecules has been attracting extensive interest and several intriguing phenomena have been reported in recent experiments, such as the emergence of zero-bias conductance peaks upon the adsorption of single-helical protein on superconducting films. Here, we study theoretically the electron transport through a two-terminal single-helical protein sandwiched between a superconducting electrode and a normal-metal one in the presence of a perpendicular magnetic field. As the proximity-induced superconductivity attenuates with the distance from superconducting media, the pairing potential along the helix axis of the single-helical protein is expected to decrease exponentially, which is characterized by the decay exponent λ and closely related to the experiments. Our results indicate that (i) a zero-bias conductance peak of 2e^2/h appears at zero temperature and the peak height (width) decreases (broadens) with increasing temperature, and (ii) this zero-bias peak can split into two peaks, which are in agreement with the experiments [see, e.g., Nano Lett. 19, 5167 (2019)]. Remarkably, Majorana zero modes are observed in this protein-superconductor setup in a wide range of model parameters, as manifested by the Z_2 topological invariant and the Majoroana oscillation. Interestingly, a specific region is demonstrated for decaying superconductivity, where topologically nontrivial and trivial zero modes coexist and the bandgap remains constant. With increasing the pairing potential, the topologically nontrivial zero modes will transform to the trivial ones without any bandgap closing-reopening, and the critical pairing potential of the phase transition attenuates exponentially with λ. Additionally, one of the two zero modes can be continuously shifted from one end of the protein toward the other end contacted by the normal-metal electrode.

We perform low-temperature magneto-conductance measurements on Cu and Au thin films with adsorbed chiral molecules and investigate their phase-coherent transport properties. Upon adsorption of chiral molecules, the spin-orbit coupling strength in Cu decreases and the Au films become ferromagnetic as evident from weak localization and antilocalization data. A theoretical model indicates that anisotropy in the molecular tilt angles, provided that the chiral molecules act as magnetic moments, induces a nonvanishing magnetic exchange interaction, causing changes in the spin-orbit coupling strength in Cu and Au. Our work adds a new viewpoint to the plethora of unique phenomena emerging from chiral molecule adsorption on materials.