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Finding high‐temperature superconductivity in light‐weight element containing compounds at atmosphere pressure is currently a research hotspot but has not been reached yet. Here it is proposed that hard or superhard materials can be promising candidates to possess the desirable high‐temperature superconductivity. By studying the electronic structures and superconducting properties of H and Li doped c‐BN within the framework of the first‐principles, it is demonstrated that the doped c‐BN are indeed good superconductors at ambient pressure after undergoing the phase transition from the insulating to metallic behavior, though holding different nature of metallization. Li doped c‐BN is predicted to exhibit the superconducting transition temperature of ≈58 K, while H doped c‐BN has stronger electron–phonon interaction and possesses a higher transition temperature of 122 K. These results and findings thus point out a new direction for exploring the ambient‐pressure higher‐temperature superconductivity in hard or superhard materials. [ABSTRACT FROM AUTHOR]

Achieving superconductivity at room temperature (RT) is a holy grail in physics. Recent discoveries on high‐Tc superconductivity in binary hydrides H3S and LaH10 at high pressure have directed the search for RT superconductors to compress hydrides with conventional electron–phonon mechanisms. Here, an exceptional family of superhydrides is predicated under high pressures, MH12 (M = Mg, Sc, Zr, Hf, Lu), all exhibiting RT superconductivity with calculated Tcs ranging from 313 to 398 K. In contrast to H3S and LaH10, the hydrogen sublattice in MH12 is arranged as quasi‐atomic H2 units. This unique configuration is closely associated with high Tc, attributed to the high electronic density of states derived from H2 antibonding states at the Fermi level and the strong electron–phonon coupling related to the bending vibration of H2 and H‐M‐H. Notably, MgH12 and ScH12 remain dynamically stable even at pressure below 100 GPa. The findings offer crucial insights into achieving RT superconductivity and pave the way for innovative directions in experimental research. [ABSTRACT FROM AUTHOR]

The electron-phonon interaction is known as one of the major mechanisms determining electrical and thermal properties. In particular, it alters the carrier transport behaviors and sets fundamental limits to carrier mobility. Establishing how electrons interact with phonons and the resulting impact on the carrier transport property is significant for the development of high-efficiency electronic devices. Here, carrier transport behavior mediated by the electron-phonon coupling in BiFeO3 epitaxial thin films is directly observed. Acoustic phonons are generated by the inverse piezoelectric effect and coupled with photocarriers. Via the electron-phonon coupling, doughnut shape carrier distribution has been observed due to the coupling between hot carriers and phonons. The hot carrier quasi-ballistic transport length can reach 340 nm within 1 ps. The results suggest an effective approach to investigating the effects of electron-phonon interactions with temporal and spatial resolutions, which is of great importance for designing and improving electronic devices.

Electron–phonon coupling (EPC) and phonon–phonon scattering (PPS) are at the core of the microscopic physics mechanisms of vast quantum materials. However, to date, there are rarely reports that these two processes can be spatially separated, although they are usually temporally detached with different characteristic lifetimes. Here, by employing ultrafast spectroscopy to investigate the photo‐carrier ultrafast dynamics in a LaCoO3 thin film on a (100) SrTiO3 substrate, intriguing evidence is found that the two interactions are indeed spatially separated. The EPC mainly occurs in the thin film, whereas PPS is largely in the substrate, especially at the several atomic layers near the interface. Across‐interface penetration and decay of optical phonons into acoustic phonons thus naturally occur. An EPC strength λEg = 0.30 is also obtained and an acoustic phonon mode at 45.3 GHz is observed. The finding lays out a cornerstone for future quantum nano device designs. [ABSTRACT FROM AUTHOR]

Electron–phonon coupling (EPC) and phonon–phonon scattering (PPS) are at the core of the microscopic physics mechanisms of vast quantum materials. However, to date, there are rarely reports that these two processes can be spatially separated, although they are usually temporally detached with different characteristic lifetimes. Here, by employing ultrafast spectroscopy to investigate the photo‐carrier ultrafast dynamics in a LaCoO3 thin film on a (100) SrTiO3 substrate, intriguing evidence is found that the two interactions are indeed spatially separated. The EPC mainly occurs in the thin film, whereas PPS is largely in the substrate, especially at the several atomic layers near the interface. Across‐interface penetration and decay of optical phonons into acoustic phonons thus naturally occur. An EPC strength λEg = 0.30 is also obtained and an acoustic phonon mode at 45.3 GHz is observed. The finding lays out a cornerstone for future quantum nano device designs. [ABSTRACT FROM AUTHOR]

To explore carbide superconductors with higher transition temperature, two novel carbon structures of cage‐network are designed and their superconductivity is studied by doping metals. MC6 and MC10 are respectively identified as C24 and C32 cage‐network structures. This study finds that both carbon structures drive strong electron–phonon interaction and can exhibit superconductivity above liquid nitrogen temperature. Importantly, the superconducting transition temperatures above 100 K are predicted to be achieved in C24‐cage‐network systems doped by Na, Mg, Al, In, and Tl at ambient pressure, which is far higher than those in graphite, fullerene, and other carbides. Meanwhile, the superconductivity of cage‐network carbides is also found to be sensitive to the electronegativity and concentration of dopant M. The result indicates that the higher transition temperatures can be obtained by optimizing the carbon‐cage‐network structures and the doping conditions. The study suggests that the carbon‐cage‐network structure is a direction to explore high‐temperature superconducting carbides. [ABSTRACT FROM AUTHOR]

Charge and thermal transport in a crystal is carried by free electrons and phonons (quantized lattice vibration), the two most fundamental quasiparticles. Above the Debye temperature of the crystal, phonon-mediated thermal conductivity (κ L) is typically limited by mutual scattering of phonons, which results in κ L decreasing with inverse temperature, whereas free electrons play a negligible role in κ L. Here, an unusual case in charge-density-wave tantalum disulfide (1T-TaS2) is reported, in which κ L is limited instead by phonon scattering with free electrons, resulting in a temperature-independent κ L. In this system, the conventional phonon-phonon scattering is alleviated by its uniquely structured phonon dispersions, while unusually strong electron-phonon (e-ph) coupling arises from its Fermi surface strongly nested at wavevectors in which phonons exhibit Kohn anomalies. The unusual temperature dependence of thermal conduction is found as a consequence of these effects. The finding reveals new physics of thermal conduction, offers a unique platform to probe e-ph interactions, and provides potential ways to control heat flow in materials with free charge carriers. The temperature-independent thermal conductivity may also find thermal management application as a special thermal interface material between two systems when the heat conduction between them needs to be maintained at a constant level.

The electron‐phonon interaction is known as one of the major mechanisms determining electrical and thermal properties. In particular, it alters the carrier transport behaviors and sets fundamental limits to carrier mobility. Establishing how electrons interact with phonons and the resulting impact on the carrier transport property is significant for the development of high‐efficiency electronic devices. Here, carrier transport behavior mediated by the electron‐phonon coupling in BiFeO3 epitaxial thin films is directly observed. Acoustic phonons are generated by the inverse piezoelectric effect and coupled with photocarriers. Via the electron‐phonon coupling, doughnut shape carrier distribution has been observed due to the coupling between hot carriers and phonons. The hot carrier quasi‐ballistic transport length can reach 340 nm within 1 ps. The results suggest an effective approach to investigating the effects of electron‐phonon interactions with temporal and spatial resolutions, which is of great importance for designing and improving electronic devices. [ABSTRACT FROM AUTHOR]

The electron‐phonon interaction is known as one of the major mechanisms determining electrical and thermal properties. In particular, it alters the carrier transport behaviors and sets fundamental limits to carrier mobility. Establishing how electrons interact with phonons and the resulting impact on the carrier transport property is significant for the development of high‐efficiency electronic devices. Here, carrier transport behavior mediated by the electron‐phonon coupling in BiFeO3 epitaxial thin films is directly observed. Acoustic phonons are generated by the inverse piezoelectric effect and coupled with photocarriers. Via the electron‐phonon coupling, doughnut shape carrier distribution has been observed due to the coupling between hot carriers and phonons. The hot carrier quasi‐ballistic transport length can reach 340 nm within 1 ps. The results suggest an effective approach to investigating the effects of electron‐phonon interactions with temporal and spatial resolutions, which is of great importance for designing and improving electronic devices. [ABSTRACT FROM AUTHOR]

Plumbene, with a structure similar to graphene, is expected to possess a strong spin–orbit coupling and thus enhances its superconducting critical temperature (Tc). In this work, a buckled plumbene‐Au Kagome superstructure grown by depositing Au on Pb(111) is investigated. The superconducting gap monitored by temperature‐dependent scanning tunneling microscopy/spectroscopy shows that the buckled plumbene‐Au Kagome superstructure not only has an enhanced Tc with respect to that of a monolayer Pb but also possesses a higher value than what owned by a bulk Pb substrate. By combining angle‐resolved photoemission spectroscopy with density functional theory, the monolayer Au‐intercalated low‐buckled plumbene sandwiched between the top Au Kagome layer and the bottom Pb(111) substrate is confirmed and the electron–phonon coupling‐enhanced superconductivity is revealed. This work demonstrates that a buckled plumbene‐Au Kagome superstructure can enhance superconducting Tc and Rashba effect, effectively triggering the novel properties of a plumbene. [ABSTRACT FROM AUTHOR]

Electrons in crystals interact closely with quantized lattice degree of freedom, determining fundamental electrodynamic behaviors and versatile correlated functionalities. However, the strength of the electron–phonon interaction is so far determined as an intrinsic value of a given material, restricting the development of potential electronic and phononic applications employing the tunable coupling strength. Here, it is demonstrated that the electron–phonon coupling in SrRuO3 can be largely controlled by multiple intuitive tuning knobs available in synthetic crystals. The coupling strength of quasi‐2D SrRuO3 is enhanced by ≈300‐fold compared with that of bulk SrRuO3. This enormous enhancement is attributed to the non‐local nature of the electron–phonon coupling within the well‐defined synthetic atomic network, which becomes dominant in the limit of the 2D electronic state. These results provide valuable opportunities for engineering the electron–phonon coupling, leading to a deeper understanding of the strongly coupled charge and lattice dynamics in quantum materials. [ABSTRACT FROM AUTHOR]

Abstract Understanding the physics of strongly correlated electronic systems has been a central issue in condensed matter physics for decades. In transition metal oxides, strong correlations characteristic of narrow d bands are at the origin of remarkable properties such as the opening of Mott gap, enhanced effective mass, and anomalous vibronic coupling, to mention a few. SrVO3 with V4+ in a 3d1 electronic configuration is the simplest example of a 3D correlated metallic electronic system. Here, the authors' focus on the observation of a (roughly) quadratic temperature dependence of the inverse electron mobility of this seemingly simple system, which is an intriguing property shared by other metallic oxides. The systematic analysis of electronic transport in SrVO3 thin films discloses the limitations of the simplest picture of e–e correlations in a Fermi liquid (FL); instead, it is shown show that the quasi‐2D topology of the Fermi surface (FS) and a strong electron–phonon coupling, contributing to dress carriers with a phonon cloud, play a pivotal role on the reported electron spectroscopic, optical, thermodynamic, and transport data. The picture that emerges is not restricted to SrVO3 but can be shared with other 3d and 4d metallic oxides.

Understanding the physics of strongly correlated electronic systems has been a central issue in condensed matter physics for decades. In transition metal oxides, strong correlations characteristic of narrow d bands are at the origin of remarkable properties such as the opening of Mott gap, enhanced effective mass, and anomalous vibronic coupling, to mention a few. SrVO3 with V4+ in a 3d1 electronic configuration is the simplest example of a 3D correlated metallic electronic system. Here, the authors' focus on the observation of a (roughly) quadratic temperature dependence of the inverse electron mobility of this seemingly simple system, which is an intriguing property shared by other metallic oxides. The systematic analysis of electronic transport in SrVO3 thin films discloses the limitations of the simplest picture of e–e correlations in a Fermi liquid (FL); instead, it is shown show that the quasi‐2D topology of the Fermi surface (FS) and a strong electron–phonon coupling, contributing to dress carriers with a phonon cloud, play a pivotal role on the reported electron spectroscopic, optical, thermodynamic, and transport data. The picture that emerges is not restricted to SrVO3 but can be shared with other 3d and 4d metallic oxides. [ABSTRACT FROM AUTHOR]

Abstract Charge and thermal transport in a crystal is carried by free electrons and phonons (quantized lattice vibration), the two most fundamental quasiparticles. Above the Debye temperature of the crystal, phonon‐mediated thermal conductivity (κL) is typically limited by mutual scattering of phonons, which results in κL decreasing with inverse temperature, whereas free electrons play a negligible role in κL. Here, an unusual case in charge‐density‐wave tantalum disulfide (1T‐TaS2) is reported, in which κL is limited instead by phonon scattering with free electrons, resulting in a temperature‐independent κL. In this system, the conventional phonon–phonon scattering is alleviated by its uniquely structured phonon dispersions, while unusually strong electron‐phonon (e‐ph) coupling arises from its Fermi surface strongly nested at wavevectors in which phonons exhibit Kohn anomalies. The unusual temperature dependence of thermal conduction is found as a consequence of these effects. The finding reveals new physics of thermal conduction, offers a unique platform to probe e‐ph interactions, and provides potential ways to control heat flow in materials with free charge carriers. The temperature‐independent thermal conductivity may also find thermal management application as a special thermal interface material between two systems when the heat conduction between them needs to be maintained at a constant level.