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The discovery of superconductivity in the Ba-La-Cu-O system (the cuprate) in the 30 K range marked a significant breakthrough, which inspired extensive exploration of oxide-based, layered superconductors to identify electron pairing with higher critical temperatures ( T c ) 1 . Despite recent observations of superconductivity in nickel oxide-based compounds (the nickelates), evidence of Cooper pairing above 30 K in a system that is isostructural to the cuprates, but without copper, at ambient pressure and without lattice compression has remained elusive 2 , 3 , 4 – 5 . Here we report superconductivity with a T c approaching 40 K under ambient pressure in d 9− x hole-doped, late rare earth, infinite-layer nickel oxide (Sm-Eu-Ca-Sr)NiO 2 thin films with negligible lattice compression, supported by observations of a zero-resistance state at 31 K and the Meissner effect. The material can be synthesized with essentially no Ruddlesden–Popper-type structural defects, exhibiting ultralow resistivity of approximately 0.01 mΩ cm, and with a residual resistivity ratio of up to 10. Our findings demonstrate the potential for achieving high-temperature superconductivity using strongly correlated d -electron metal oxides beyond copper as the building blocks for superconductivity, and offering a promising platform for further exploration and understanding of high-temperature Cooper pairing. Superconductivity at temperatures approaching 40 K for a hole-doped nickel oxide that is isostructural with cuprate superconductors demonstrates the existence of a broader family of materials and potential for achieving higher-temperature superconductivity.

Near the boundary between ordered and disordered quantum phases, several experiments have demonstrated metallic behaviour that defies the Landau Fermi paradigm 1 – 5 . In moiré heterostructures, gate-tuneable insulating phases driven by electronic correlations have been recently discovered 6 – 23 . Here, we use transport measurements to characterize metal–insulator transitions (MITs) in twisted WSe 2 near half filling of the first moiré subband. We find that the MIT as a function of both density and displacement field is continuous. At the metal–insulator boundary, the resistivity displays strange metal behaviour at low temperatures, with dissipation comparable to that at the Planckian limit. Further into the metallic phase, Fermi liquid behaviour is recovered at low temperature, and this evolves into a quantum critical fan at intermediate temperatures, before eventually reaching an anomalous saturated regime near room temperature. An analysis of the residual resistivity indicates the presence of strong quantum fluctuations in the insulating phase. These results establish twisted WSe 2 as a new platform to study doping and bandwidth-controlled metal–insulator quantum phase transitions on the triangular lattice. Metal-to-insulator transitions are characterized in twisted WSe, revealing strange metal behaviour and quantum criticality at low temperatures.

Fluid flow through fractured media is typically governed by the distribution of fracture apertures, which are in turn governed by stress. Consequently, understanding subsurface stress is critical for understanding and predicting subsurface fluid flow. Although laboratory‐scale studies have established a sensitive relationship between effective stress and bulk electrical conductivity in crystalline rock, that relationship has not been extensively leveraged to monitor stress evolution at the field scale using electrical or electromagnetic geophysical monitoring approaches. In this paper we demonstrate the use time‐lapse 3‐dimensional (4D) electrical resistivity tomography to image perturbations in the stress field generated by pressurized borehole packers deployed during shear‐stimulation attempts in a 1.25 km deep metamorphic crystalline rock formation. Plain Language Summary Time‐lapse electrical geophysical sensing is used to image 3D changes in rock stress generated by an isolated and pressurized interval of a borehole in a deep, dense, fractured rock formation. Key Points Remotely monitoring stress is challenging but important for relating geomechanical behavior to flow pathways during energy production Bulk electrical conductivity is sensitive to stress in crystalline rock Time‐lapse electrical resistivity tomography can be used to remotely monitor 3D changes in effective stress

Advances in physical vapor deposition techniques have led to a myriad of quantum materials and technological breakthroughs, affecting all areas of nanoscience and nanotechnology which rely on the innovation in synthesis. Despite this, one area that remains challenging is the synthesis of atomically precise complex metal oxide thin films and heterostructures containing “stubborn” elements that are not only nontrivial to evaporate/sublimate but also hard to oxidize. Here, we report a simple yet atomically controlled synthesis approach that bridges this gap. Using platinum and ruthenium as examples, we show that both the low vapor pressure and the difficulty in oxidizing a “stubborn” element can be addressed by using a solid metal-organic compound with significantly higher vapor pressure and with the added benefits of being in a preoxidized state along with excellent thermal and air stability. We demonstrate the synthesis of high-quality single crystalline, epitaxial Pt, and RuO₂ films, resulting in a record high residual resistivity ratio (=27) in Pt films and low residual resistivity, ∼6 μΩ·cm, in RuO₂ films. We further demonstrate, using SrRuO₃ as an example, the viability of this approach for more complex materials with the same ease and control that has been largely responsible for the success of the molecular beam epitaxy of III-V semiconductors. Our approach is a major step forward in the synthesis science of “stubborn” materials, which have been of significant interest to the materials science and the condensed matter physics community.

The polyaniline nano fiber was deposited on glass and ITO by simple and economic oxidative polymerization technique. The thickness of PANI Nano fiber deposited on glass and ITO found to be 190 nm and 210 nm respectively which are measured by gravimetric weight difference method. The XRD study shows the amorphous nature of both the films with decrease in intensity for PANI deposited on ITO. SEM micrograph shows that PANI is deposited uniformly and no more change was observed. FTIR study represents the formation of PANI emeraldine salt, whereas, the optical absorbance spectra indicates three characteristic peaks with higher intensity of absorption in case of PANI deposited on ITO. The DC electrical resistivity of PANI deposited on glass and ITO was investigated by home made two probe resistivity set up and the resistivity was found to be 5.49×106 Ω.cm for PANI deposited on glass and 1.96×103 Ω.cm PANI deposited on ITO. Furthermore, the ammonia gas sensing study of as deposited PANI thin film was investigated by gas sensor system with different concentration of gas and higher sensitivity i.e.17.7% found to be for 100 ppm of Ammonia gas also the response and recovery time found to be 24 sec and 26 sec respectively.

Piezoresistivity is an electromechanical effect characterized by the reversible change in the electrical resistivity with strain. It is useful for electrical-resistance-based strain/stress sensing. The resistivity can be the volumetric, interfacial or surface resistivity, though the volumetric resistivity is most meaningful scientifically. Because the irreversible resistivity change (due to damage or an irreversible microstructural change) adds to the reversible change that occurs at lower strains, the inclusion of the irreversible effect makes the piezoresistivity appear stronger than the inherent effect. This paper focuses on the inherent piezoresistivity that occurs without irreversible resistivity changes. The effect is described by the gage factor (GF), which is defined as the fractional change in resistance per unit strain. The GF can be positive or negative. Strong piezoresistivity involves the magnitude of the fractional change in resistivity much exceeding the strain magnitude. The reversible effect of strain on the electrical connectivity is the primary piezoresistivity mechanism. Giant piezoresistivity is characterized by GF ≥ 500. This critical review with 209 references covers the theory, mechanisms, methodology and status of piezoresistivity, and provides the first review of the emerging field of giant piezoresistivity. Piezoresistivity is exhibited by electrically conductive materials, particularly metals, carbons and composite materials with conductive fillers and nonconductive matrices. They include functional and structural materials. Piezoresistivity enables structural materials to be self-sensing. Unfortunately, GF was incorrectly or unreliably reported in a substantial fraction of the publications, due to the pitfalls systematically presented here. The most common pitfall involves using the two-probe method for the resistance measurement.

By applying pressures up to 42 GPa on the nitrogen-doped lutetium hydride (LuH 2+ x N y ), we have found a gradual change of color from dark-blue to pink-violet in the pressure region of about 12 to 21 GPa. The temperature dependence of resistivity under pressures up to 50.5 GPa shows progressively optimized metallic behavior with pressure. Interestingly, in the pressure region for the color change, a clear decrease of resistivity is observed with the increase of pressure, which is accompanied by a clear increase of the residual resistivity ratio (RRR). Fitting to the low temperature resistivity gives exponents of about 2, suggesting a Fermi-liquid behavior in the low temperature region. The general behavior in a wide temperature region suggests that the electron-phonon scattering is still the dominant one. The magnetoresistance up to 9 T in the state under a pressure of 50.5 GPa shows an almost negligible effect, which suggests that the electric conduction in the pink-violet state is dominated by a single band. It is highly desired to have theoretical efforts in understanding the evolution of color and resistivity in this interesting system.

Cement-based sensors with hybrid conductive fillers using both carbon fibers (CFs) and multi-walled carbon nanotubes (MWCNTs) were experimentally investigated in this study. The self-sensing capacities of cement-based composites with only CFs or MWCNTs were found based on preliminary tests. The results showed that the percolation thresholds of CFs and MWCNTs were 0.5–1.0 vol.% and 1.0 vol.%, respectively. Based on these results, the feasibility of self-sensing composites with four different amounts of CFs and MWCNTs was considered under cyclic compression loads. When the amount of incorporated CFs increased and the amount of incorporated MWCNTs decreased, the self-sensing capacity of the composites was reduced. It was concluded that cement-based composites containing both 0.1 vol.% CFs and 0.5 vol.% MWCNTs could be an alternative to cement-based composites with 1.0 vol.% MWCNTs in order to achieve equivalent self-sensing performance at half the price. The gauge factor (GF) for that composite was 160.3 with an R-square of 0.9274 in loading stages I and II, which was similar to the GF of 166.6 for the composite with 1.0 vol.% MWCNTs.

Geophysical surveys for cavity detection are one of the most common nearsurface applications. The usage of resistivity methods is also very straightforward for the air-filled underground voids, which should have theoretically infinite resistivity in the ERT image. In the first part of the paper, we deal with the comparison of detectability of the cavity by several types of the electrode arrays, the second part discusses the effect of a thin layer around the cavity itself, by means of 2D modelling. The presence of this layer deforms the resistivity image significantly as the resistive anomaly could be turned into a conductive one, in the case when the thin layer is more conductive than the background environment. From the electrical array analysis for the model situation a dipole-dipole and combined pole-dipole shows the best results among the other involved electrical arrays.

Landslide damming is a widespread phenomenon worldwide and significantly affects the evolution of fluvial landscapes. However, it is rarely witnessed from an antiquities perspective, and the case for observing their internal structure is challenging. We attempt to visualize the subsurface structure and understand the likely breaching mechanism of the late Pleistocene Diexi gigantic landslide dam (longevity of ~ 10 ka), using electrical resistivity tomography (ERT) method. Eight ERT measurements on the Diexi dam body revealed high resistivity zones near the periphery and lower resistivity zones in the middle portion of the profiles. Geomorphological mapping based on the LiDAR data determined the boundary of the landslide. Field investigation found that zones of low resistivity were connected to a ditched gully. Because breaching such an enormous lake with a total area of 21.4 km2 dammed by a gigantic landslide body with intact rocks was not likely by overtopping alone. The authors postulate that differential seepage of water from the gullies through the landslide debris could have accelerated the undercutting erosion of the otherwise stable Diexi dam. Utilizing geophysical techniques, along with field geomorphology works, can provide valuable information on the evolution of a gigantic paleo-landslide dam, which has real implications for the stability evaluation and forecast of future landslide dams.