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Recently, superconductivity was discovered with a superconducting transition temperature (Tc) of 2 K in strained (110)-oriented RuO2 films grown on TiO2(110) single-crystal substrates. In this work, we predict and realize superconductivity in strained (100)-oriented RuO2 thin films grown on TiO2(100) single-crystal substrates. We show that while density functional theory predicts the Tc of strained RuO2(100) films to be even higher than the RuO2(110) films, our transport and angle-resolved photoemission spectroscopy measurements find the Tc to be about 1 K in strained RuO2(100) films grown on TiO2(100) substrates. Nonetheless, the thickness dependence of the Tc follows a similar trend in both cases. Our scanning SQUID measurements reveal a local superfluid response, indicating a 100 mK inhomogeneity in Tc over a 100 μm scale. 

The discovery of superconductivity in La3Ni2O7 under pressure has motivated the investigation of a parent spin density wave (SDW) state, which could provide the underlying pairing interaction. Here, we employ resonant soft x-ray scattering and polarimetry on thin films of bilayer La3Ni2O7 to determine that the magnetic structure of the SDW forms unidirectional diagonal spin stripes with moments lying within the NiO2 plane and perpendicular to QSDW, but without evidence of the strong charge disproportionation typically associated with other nickelates. These stripes form anisotropic domains with shorter correlation lengths perpendicular versus parallel to QSDW, revealing nanoscale rotational and translational symmetry breaking analogous to the cuprate and Fe-based superconductors, with possible Bloch-like antiferromagnetic domain walls separating orthogonal domains. 

The ability to visualize crystalline defects and lattice distortions at the nanoscale holds profound implications for enhancing material properties and optimizing their design. Bragg coherent diffractive imaging (BCDI) emerged as a powerful technique due to its simplicity and high sensitivity to lattice strains. This review examines recent advancements in BCDI, highlighting its capability to uncover defects under various experimental conditions. It discusses fundamental principles and data analysis intricacies as well as BCDI's applications in characterizing structural and functional materials. Furthermore, it offers perspectives on the current limitations of BCDI and the potential implications of synchrotron upgrades. By providing these insights, the review aims to enhance the role of BCDI in advancing materials science and nanotechnology. 

Abstract Discontinuous solid-solid phase transformations play a pivotal role in determining the properties of rechargeable battery electrodes. By leveraging operando Bragg Coherent Diffractive Imaging (BCDI), we investigate the discontinuous phase transformation in Li_xNi_0.5Mn_1.5O₄within an operational Li metal coin cell. Throughout Li-intercalation, we directly observe the nucleation and growth of the Li-rich phase within the initially charged Li-poor phase in a 500 nm particle. Supported by the microelasticity model, the operando imaging unveils an evolution from a curved coherent to a planar semi-coherent interface driven by dislocation dynamics. Our data indicates negligible kinetic limitations from interface propagation impacting the transformation kinetics, even at a discharge rate of C/2 (80 mA/g). This study highlights BCDI’s capability to decode complex operando diffraction data, offering exciting opportunities to study nanoscale phase transformations with various stimuli. 

Unlike naturally occurring oxide crystals such as ruby and gemstones, there are no naturally occurring nitride crystals because the triple bond of the nitrogen molecule is one of the strongest bonds in nature. Here, we report that when the transition metal scandium is subjected to molecular nitrogen, it self-catalyzes to break the nitrogen triple bond to form highly crystalline layers of ScN, a semiconductor. This reaction proceeds even at room temperature. Self-activated ScN films have a twin cubic crystal structure, atomic layering, and electronic and optical properties comparable to plasma-based methods. We extend our research to showcase Sc’s scavenging effect and demonstrate self-activated ScN growth under various growth conditions and on technologically significant substrates, such as 6H–SiC, AlN, and GaN. Ab initio calculations elucidate an energetically efficient pathway for the self-activated growth of crystalline ScN films from molecular N2. The findings open a new pathway to ultralow-energy synthesis of crystalline nitride semiconductor layers and beyond. 

Abstract Mott metal–insulator transitions possess electronic, magnetic, and structural degrees of freedom promising next‐generation energy‐efficient electronics. A previously unknown, hierarchically ordered, and anisotropic supercrystal state is reported and its intrinsic formation characterized in‐situ during a Mott transition in a Ca₂RuO₄thin film. Machine learning‐assisted X‐ray nanodiffraction together with cryogenic electron microscopy reveal multi‐scale periodic domain formation at and below the film transition temperature (T_Film ≈ 200–250 K) and a separate anisotropic spatial structure at and aboveT_Film. Local resistivity measurements imply an intrinsic coupling of the supercrystal orientation to the material's anisotropic conductivity. These findings add a new degree of complexity to the physical understanding of Mott transitions, opening opportunities for designing materials with tunable electronic properties. 

Bragg coherent X-ray diffractive imaging is a cutting-edge method for recovering three-dimensional crystal structure with nanoscale resolution. Phase retrieval provides an atomic displacement parallel to the Bragg peak reciprocal lattice vector. The derivative of the displacement along the same vector provides the normal strain field, which typically serves as a proxy for any structural changes. In this communication it is found that the other component of the displacement gradient, perpendicular to the reciprocal lattice vector, provides additional information from the experimental data collected from nanocrystals with mobile dislocations. Demonstration on published experimental data show how the perpendicular component of the displacement gradient adds to existing analysis, enabling an estimate for the external stresses, pinpointing the location of surface dislocations, and predicting the dislocation motion in in situ experiments.