Creation of Multi-Principal Element Alloy NiCoCr Nanostructures via Nanosecond Laser-Induced Dewetting.

The multi-principal element alloy nanoparticles (MPEA NPs), a new class of nanomaterials, present a highly rewarding opportunity to explore new or vastly different functional properties than the traditional mono/bi/multimetallic nanostructures due to their unique characteristics of atomic-level homogeneous mixing of constituent elements in the nanoconfinements. Here, the successful creation of NiCoCr nanoparticles, a well-known MPEA system is reported, using ultrafast nanosecond laser-induced dewetting of alloy thin films. Nanoparticle formation occurs by spontaneously breaking the energetically unstable thin films in a melt state under laser-induced hydrodynamic instability and subsequently accumulating in a droplet shape via surface energy minimization. While NiCoCr alloy shows a stark contrast in physical properties compared to individual metallic constituents, i.e., Ni, Co, and Cr, yet the transient nature of the laser-driven process facilitates a homogeneous distribution of the constituents (Ni, Co, and Cr) in the nanoparticles. Using high-resolution chemical analysis and scanning nanodiffraction, the environmental stability and grain arrangement in the nanoparticles are further investigated. Thermal transport simulations reveal that the ultrashort (≈100 ns) melt-state lifetime of NiCoCr during the dewetting event helps retain the constituent elements in a single-phase solid solution with homogenous distribution and opens the pathway to create the unique MPEA nanoparticles with laser-induced dewetting process.

Enhanced mechanical properties of Q-carbon nanocomposites by nanosecond pulsed laser annealing.

Q-carbon is a metastable phase of carbon formed by melting and subsequently quenching amorphous carbon films by a nanosecond laser in a super undercooled state. As Q-carbon is a material harder than diamond, it makes an excellent reinforcing component inside the softer matrix of a composite coating. In this report, we present a single-step strategy to fabricate adherent coatings of hard and lubricating Q-carbon nanocomposites. These nanocomposites consist of densely-packed sp 3-rich Q-carbon (82% sp 3), and sp 2-rich α-carbon (40% sp 3) amorphous phases. The nanoindentation tests show that the Q-carbon nanocomposites exhibit a hardness of 67 GPa (Young's modulus âˆ¼ 840 GPa) in contrast to the soft α-carbon (hardness âˆ¼ 18 GPa). The high hardness of Q-carbon nanocomposites results in 0.16 energy dispersion coefficient, in comparison with 0.74 for α-carbon. The soft α-carbon phase provides lubrication, resulting in low friction and wear coefficients of 0.09 and 1 × 10-6, respectively, against the diamond tip. The nanoscale dispersion of hard Q-carbon and soft α-carbon phases in the Q-carbon nanocomposites enhances the toughness of the coatings. We present detailed structure-property correlations to understand enhancement in the mechanical properties of Q-carbon nanocomposites. This work provides insights into the characteristics of Q-carbon nanocomposites and advances carbon-based superhard materials for longer lasting protective coatings and related applications.

Quantum-Spillover-Enhanced Surface-Plasmonic Absorption at the Interface of Silver and High-Index Dielectrics.

We demonstrate an unexpectedly strong surface-plasmonic absorption at the interface of silver and high-index dielectrics based on electron and photon spectroscopy. The measured bandwidth and intensity of absorption deviate significantly from the classical theory. Our density-functional calculation well predicts the occurrence of this phenomenon. It reveals that due to the low metal-to-dielectric work function at such interfaces, conduction electrons can display a drastic quantum spillover, causing the interfacial electron-hole pair production to dominate the decay of surface plasmons. This finding can be of fundamental importance in understanding and designing quantum nanoplasmonic devices that utilize noble metals and high-index dielectrics.

Engineering Pt/Co/AlOxheterostructures to enhance the Dzyaloshinskii-Moriya interaction.

The study of interfacial Dzyaloshinskii-Moriya interaction (DMI) in perpendicularly magnetized structurally asymmetric heavy metal/ferromagnet multilayer systems is of high importance due to the formation of chiral magnetic textures in the presence of DMI. Here, we report the impact of cobalt oxidation at the Co/AlOxinterface in Pt/Co/AlOxtrilayer structures on the DMI by varying the post-growth annealing time, Al thickness and substrate. To quantify DMI we employed magneto-optical imaging of the asymmetric domain wall expansion, hysteresis loop shift, and spin-wave spectroscopy techniques. We further correlated the Co oxidation with low-temperature Hall effect measurements and x-ray photoelectron spectroscopy. Our results emphasize the importance of full characterization of the magnetic films that could be used for magnetic random access memory technologies when subjected to the semiconductor temperature processing conditions, as the magnetic interactions are critical for device performance and can be highly sensitive to oxidation and other effects.

Fabricating Graphene Oxide/h-BN Metal Insulator Semiconductor Diodes by Nanosecond Laser Irradiation.

To employ graphene's rapid conduction in 2D devices, a heterostructure with a broad bandgap dielectric that is free of traps is required. Within this paradigm, h-BN is a good candidate because of its graphene-like structure and ultrawide bandgap. We show how to make such a heterostructure by irradiating alternating layers of a-C and a-BN film with a nanosecond excimer laser, melting and zone-refining constituent layers in the process. With Raman spectroscopy and ToF-SIMS analyses, we demonstrate this localized zone-refining into phase-pure h-BN and rGO films with distinct Raman vibrational modes and SIMS profile flattening after laser irradiation. Furthermore, in comparing laser-irradiated rGO-Si MS and rGO/h-BN/Si MIS diodes, the MIS diodes exhibit an increased turn-on voltage (4.4 V) and low leakage current. The MIS diode I-V characteristics reveal direct tunneling conduction under low bias and Fowler-Nordheim tunneling in the high-voltage regime, turning the MIS diode ON with improved rectification and current flow. This study sheds light on the nonequilibrium approaches to engineering h-BN and graphene heterostructures for ultrathin field effect transistor device development.

Spin Engineering of VO2 Phase Transitions and Removal of Structural Transition.

Vanadium dioxide undergoes a metal-to-insulator transition, where the energy of electron-electron, electron-lattice, spin-spin, and spin-lattice interactions are of the same order of magnitude. This leads to the coexistence of electronic and structural transitions in VO2 that limit the lifetime and speed of VO2-based devices. However, the closeness of interaction energy of lattice-electron-spin can be turned into an opportunity to induce some transitions while pinning others via external stimuli. That is, the contribution of spin, charge, orbital, and lattice degrees of freedom can be manipulated. In this study, spin engineering has been exploited to affect the spin-related interactions in VO2 by introducing a ferromagnetic Ni layer. The coercivity in the Ni layer is engineered by controlling the shape anisotropy via kinetics of growth. Using spin engineering, the structural pinning of the monoclinic M2 phase of VO2 is successfully achieved, while the electronic and magnetic transitions take place.

Enhanced Vapor Transmission Barrier Properties via Silicon-Incorporated Diamond-Like Carbon Coating.

In this study, we describe reducing the moisture vapor transmission through a commercial polymer bag material using a silicon-incorporated diamond-like carbon (Si-DLC) coating that was deposited using plasma-enhanced chemical vapor deposition. The structure of the Si-DLC coating was analyzed using scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, selective area electron diffraction, and electron energy loss spectroscopy. Moisture vapor transmission rate (MVTR) testing was used to understand the moisture transmission barrier properties of Si-DLC-coated polymer bag material; the MVTR values decreased from 10.10 g/m2 24 h for the as-received polymer bag material to 6.31 g/m2 24 h for the Si-DLC-coated polymer bag material. Water stability tests were conducted to understand the resistance of the Si-DLC coatings toward moisture; the results confirmed the stability of Si-DLC coatings in contact with water up to 100 °C for 4 h. A peel-off adhesion test using scotch tape indicated that the good adhesion of the Si-DLC film to the substrate was preserved in contact with water up to 100 °C for 4 h.

Nonequilibrium Structural Evolution of Q-Carbon and Interfaces.

Q-carbon is a densely packed metastable phase of carbon formed by ultrafast quenching of carbon melt in a super-undercooled state. After quenching, diamond tetrahedra are randomly packed with >80% packing efficiency. This discovery has opened a pathway to fabricate various interesting heterostructures following the highly nonequilibrium route of nanosecond pulsed laser annealing. In the present work, we demonstrate the evolution of Q-carbon/α-carbon and Q-carbon/diamond heterostructures with atomically sharp interfaces, controlled via varying solidification rates of the undercooled C melt. This structure consists of ultrahard Q-carbon (∼80% sp3 and rest sp2) with an overlayer of soft α-carbon (∼40% sp3) on the inert c-Al2O3 substrate. Using high-resolution scanning transmission electron microscopy and Raman spectroscopy analysis, we present the formation of the highly dense Q-carbon/α-carbon bilayer structure with distinctly different atomic and electronic structures. The laser-solid interaction simulations coupled with atomistic ab initio modeling further confirm the conversion of C melt into Q-carbon by achieving maximum undercooling near the substrate and further into α-carbon with a decrease in regrowth velocity (<6 m/s) away from the substrate. We present details of the evolution of heterointerfaces formed from carbon melt for designing heterostructures far from equilibrium for various functional applications by using pulsed laser processing.

∑3 Twin Boundaries in Gd2Ti2O7 Pyrochlore: Pathways for Oxygen Migration.

Understanding the chemistry at twin boundaries (TB) is a well-recognized challenge, which could enable the capabilities to manipulate the functional properties in complex oxides. The study of this atomic imperfection becomes even more important, as the presence of twin boundaries has been widely observed in materials, regardless of the dimensionalities, due to the complexities in growth methods. In the present study, we provide atomic-scale insights into a ∑3(111̅) ⟨11̅0⟩ twin boundary present in pyrochlore-structured Gd2Ti2O7 using atomic-resolution electron microscopy and atomistic modeling. The formation of the observed TB occurs along (111̅) with a 71° angle between two symmetrically arranged crystals. We observe distortions (∼3 to 5% strain) in the atomic structure at the TB with an increase in Gd-Gd (0.66 ± 0.03 nm) and Ti-Ti (0.65 ± 0.02 nm) bond lengths in the (11̅0) plane, as compared to 0.63 nm in the ordered structure. Using atomistic modeling, we further calculate the oxygen migration barrier for vacancy hopping at 48f-48f sites in the pyrochlore structure, which is the primary diffusion pathway for fast oxygen transport. The mean migration barrier is lowered by ∼25% to 0.9 eV at the TB as compared to 1.23 eV in the bulk, suggesting the ease in oxygen transport through the ∑3 twin boundaries. Overall, these results offer a critical understanding of the atomic arrangement at the twin boundaries in pyrochlores, leading to control of the interplay between defects and properties.

High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures.

Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH3) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al2O3) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al2O3 or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures.

Electrical Transition in Isostructural VO2 Thin-Film Heterostructures.

Control over the concurrent occurrence of structural (monoclinic to tetragonal) and electrical (insulator to the conductor) transitions presents a formidable challenge for VO2-based thin film devices. Speed, lifetime, and reliability of these devices can be significantly improved by utilizing solely electrical transition while eliminating structural transition. We design a novel strain-stabilized isostructural VO2 epitaxial thin-film system where the electrical transition occurs without any observable structural transition. The thin-film heterostructures with a completely relaxed NiO buffer layer have been synthesized allowing complete control over strains in VO2 films. The strain trapping in VO2 thin films occurs below a critical thickness by arresting the formation of misfit dislocations. We discover the structural pinning of the monoclinic phase in (10 ± 1 nm) epitaxial VO2 films due to bandgap changes throughout the whole temperature regime as the insulator-to-metal transition occurs. Using density functional theory, we calculate that the strain in monoclinic structure reduces the difference between long and short V-V bond-lengths (ΔV-V) in monoclinic structures which leads to a systematic decrease in the electronic bandgap of VO2. This decrease in bandgap is additionally attributed to ferromagnetic ordering in the monoclinic phase to facilitate a Mott insulator without going through the structural transition.

Vacancy-Driven Robust Metallicity of Structurally Pinned Monoclinic Epitaxial VO2 Thin Films.

Vanadium dioxide (VO2) is a strongly correlated material with 3d electrons, which exhibits temperature-driven insulator-to-metal transition with a concurrent change in the crystal symmetry. Interestingly, even modest changes in stoichiometry-induced orbital occupancy dramatically affect the electrical conductivity of the system. Here, we report a successful transformation of epitaxial monoclinic VO2 thin films from a conventionally insulating to permanently metallic behavior by manipulating the electron correlations. These ultrathin (∼10 nm) epitaxial VO2 films were grown on NiO(111)/Al2O3(0001) pseudomorphically, where the large misfit between NiO and Al2O3 were fully relaxed by domain-matching epitaxy. Complete conversion from an insulator to permanent metallic phase is achieved through injecting oxygen vacancies ( x ∼ 0.20 ± 0.02) into the VO2- x system via annealing under high vacuum (∼5 × 10-7 Torr) and increased temperature (450 °C). Systematic introduction of oxygen vacancies partially converts V4+ to V3+ and generates unpaired electron charges which result in the emergence of donor states near the Fermi level. Through the detailed study of the vibrational modes by Raman spectroscopy, hardening of the V-V vibrational modes and stabilization of V-V dimers are observed in vacuum-annealed VO2 films, providing conclusive evidence for stabilization of a monoclinic phase. This ultimately leads to convenient free-electron transport through the oxygen-deficient VO2- x thin films, resulting in metallic characteristics at room temperature. With these results, we propose a defect engineering pathway through the control of oxygen vacancies to tune electrical and optical properties in epitaxial monoclinic VO2.

Reversible defect engineering in graphene grain boundaries.

Research efforts in large area graphene synthesis have been focused on increasing grain size. Here, it is shown that, beyond 1 µm grain size, grain boundary engineering determines the electronic properties of the monolayer. It is established by chemical vapor deposition experiments and first-principle calculations that there is a thermodynamic correlation between the vapor phase chemistry and carbon potential at grain boundaries and triple junctions. As a result, boundary formation can be controlled, and well-formed boundaries can be intentionally made defective, reversibly. In 100 µm long channels this aspect is demonstrated by reversibly changing room temperature electronic mobilities from 1000 to 20,000 cm2 V-1 s-1. Water permeation experiments show that changes are localized to grain boundaries. Electron microscopy is further used to correlate the global vapor phase conditions and the boundary defect types. Such thermodynamic control is essential to enable consistent growth and control of two-dimensional layer properties over large areas.

Synthesis of TiB2/Fe-Cr-Al nanocomposite powder.

In this study, a route for synthesizing TiB2/Fe-Cr-Al nanocomposite is proposed via high energy ball milling by using directly coarse powders of TiB2, Fe, Cr and Al. Various compositions of these powder mixtures are milled up to 48 hrs to investigate the effect of composition on the crystalline refinement. The crystalline size is analyzed by an X-ray diffractometer for powder samples containing 30 to 100 wt% TiB2 (the rest of the powder consists of Fe-20 wt%Cr-5 wt%Al composition). The crystalline size after 48 hrs of ball milling decreases with increasing TiB2, and then again increases after reaching a minimum value of 18 nm at 70% TiB2. By transmission electron microscopic analysis, it is confirmed that particles of TiB2 are significantly reduced and finely dispersed in the Fe-Cr-Al matrix. The particle size of TiB2 is found around 20-25 nm, reinforced in the matrix. Considering the results of this study, the proposed mechanical milling route can be recommended as a promising way for fabrication of TiB2/Fe-Cr-Al nanocomposite powder.

Magnetic relaxation and three-dimensional critical fluctuations in B-doped Q-carbon - a high-temperature superconductor.

Dimensional fluctuations and magnetic relaxations in high-temperature superconductors are key considerations for practical applications in high-speed electronic devices. We report the creep of trapped magnetic flux and three-dimensional critical fluctuations near the superconducting transition temperature (Tc = 36 K) in B-doped amorphous Q-carbon. The superconducting phase in B-doped Q-carbon is formed by nanosecond pulsed laser melting in a super undercooled state followed by subsequent quenching. Time-dependent magnetic moment measurements in the B-doped Q-carbon follow the Anderson-Kim logarithmic decay model with the calculated value of pinning potential to be 0.75 eV at 1 T near Tc. There is also strong evidence of three-dimensional (3D) critical fluctuations near Tc in B-doped Q-carbon. The crossover from 2D to 3D critical fluctuations is seen at T/Tc = 1.01 as compared to T/Tc = 1.11 in conventional Bardeen-Cooper-Schrieffer (BCS) high-temperature superconductors. These critical fluctuations indicate moderate to strong electron-phonon coupling in B-doped Q-carbon. The isomagnetic temperature-dependent resistivity measurements reveal a broadening of superconducting transition width with increasing magnetic field. The upper critical field (Hc2(0)) is calculated to be 5.6 T using the power law. Finally, the superconducting region is determined in B-doped Q-carbon, as the three vertices of the superconducting region are calculated as Tc = 36.0 K, Jc = 2.9 × 109 A cm-2 and Hc2 = 5.6 T. The temperature-dependent magnetic moment and resistivity measurements also validate B-doped Q-carbon as a BCS type-II superconductor. B concentration in Q-carbon can be increased up to 50 at% by a nanosecond laser melting and quenching technique, thus providing an ideal platform for near room-temperature superconductivity.

An optimized sample preparation approach for atomic resolution in situ studies of thin films.

This work provides the details of a simple and reliable method with less damage to prepare electron transparent samples for in situ studies in scanning/transmission electron microscopy. In this study, we use epitaxial VO2 thin films grown on c-Al2 O3 by pulsed laser deposition, which have a monoclinic-rutile transition at ~68°C. We employ an approach combining conventional mechanical wedge-polishing and Focused Ion beam to prepare the electron transparent samples of epitaxial VO2 thin films. The samples are first mechanically wedge-polished and ion-milled to be electron transparent. Subsequently, the thin region of VO2 films are separated from the rest of the polished sample using a focused ion beam and transferred to the in situ electron microscopy test stage. As a critical step, carbon nanotubes are used as connectors to the manipulator needle for a soft transfer process. This is done to avoid shattering of the brittle substrate film on the in situ sample support stage during the transfer process. We finally present the atomically resolved structural transition in VO2 films using this technique. This approach significantly increases the success rate of high-quality sample preparation with less damage for in situ studies of thin films and reduces the cost and instrumental/user errors associated with other techniques. The present work highlights a novel, simple, reliable approach with reduced damage to make electron transparent samples for atomic-scale insights of temperature-dependent transitions in epitaxial thin film heterostructures using in situ TEM studies.

Oxygen Effect on the Properties of Epitaxial (110) La0.7Sr0.3MnO3 by Defect Engineering.

The multiferroic properties of mixed valence perovskites such as lanthanum strontium manganese oxide (La0.7Sr0.3MnO3) (LSMO) demonstrate a unique dependence on oxygen concentration, thickness, strain, and orientation. To better understand the role of each variable, a systematic study has been performed. In this study, epitaxial growth of LSMO (110) thin films with thicknesses ∼15 nm are reported on epitaxial magnesium oxide (111) buffered Al2O3 (0001) substrates. Four LSMO films with changing oxygen concentration have been investigated. The oxygen content in the films was controlled by varying the oxygen partial pressure from 1 × 10-4 to 1 × 10-1 Torr during deposition and subsequent cooldown. X-ray diffraction established the out-of-plane and in-plane plane matching to be (111)MgO ∥ (0001)Al2O3 and ⟨11̅0⟩MgO ∥ ⟨101̅0⟩Al2O3 for the buffer layer with the substrate, and an out-of-plane lattice matching of (110)LSMO ∥ (111)MgO for the LSMO layer. For the case of the LSMO growth on MgO, a novel growth mode has been demonstrated, showing that three in-plane matching variants are present: (i) ⟨11̅0⟩LSMO ∥ ⟨11̅0⟩MgO, (ii) ⟨11̅0⟩LSMO ∥ ⟨101̅⟩MgO, and (iii) ⟨11̅0⟩LSMO ∥ ⟨01̅1⟩MgO. The atomic resolution scanning transmission electron microscopy (STEM) images were taken of the interfaces that showed a thin, ∼2 monolayer intermixed phase while high-angle annular dark field (HAADF) cross-section images revealed 4/5 plane matching between the film and the buffer and similar domain sizes between different samples. Magnetic properties were measured for all films and the gradual decrease in saturation magnetization is reported with decreasing oxygen partial pressure during growth. A systematic increase in the interplanar spacing was observed by X-ray diffraction of the films with lower oxygen concentration, indicating the decrease in the lattice constant in the plane due to the point defects. Samples demonstrated an insulating behavior for samples grown under low oxygen partial pressure and semiconducting behavior for the highest oxygen partial pressures. Magnetotransport measurements showed ∼36.2% decrease in electrical resistivity with an applied magnetic field of 10 T at 50 K and ∼1.3% at room temperature for the highly oxygenated sample.

Sculpting Nanoscale Functional Channels in Complex Oxides Using Energetic Ions and Electrons.

The formation of metastable phases has attracted significant attention because of their unique properties and potential functionalities. In the present study, we demonstrate the phase conversion of energetic-ion-induced amorphous nanochannels/tracks into a metastable defect fluorite in A2B2O7 structured complex oxides by electron irradiation. Through in situ electron irradiation experiments in a scanning transmission electron microscope, we observe electron-induced epitaxial crystallization of the amorphous nanochannels in Yb2Ti2O7 into the defect fluorite. This energetic-electron-induced phase transformation is attributed to the coupled effect of ionization-induced electronic excitations and local heating, along with subthreshold elastic energy transfers. We also show the role of ionic radii of A-site cations (A = Yb, Gd, and Sm) and B-site cations (Ti and Zr) in facilitating the electron-beam-induced crystallization of the amorphous phase to the defect-fluorite structure. The formation of the defect-fluorite structure is eased by the decrease in the difference between ionic radii of A- and B-site cations in the lattice. Molecular dynamics simulations of thermal annealing of the amorphous phase nanochannels in A2B2O7 draw parallels to the electron-irradiation-induced crystallization and confirm the role of ionic radii in lowering the barrier for crystallization. These results suggest that employing guided electron irradiation with atomic precision is a useful technique for selected area phase formation in nanoscale printed devices.

High-Temperature Superconductivity in Boron-Doped Q-Carbon.

We report high-temperature superconductivity in B-doped amorphous quenched carbon (Q-carbon). This phase is formed after nanosecond laser melting of B-doped amorphous carbon films in a super-undercooled state and followed by rapid quenching. Magnetic susceptibility measurements show the characteristics of type-II Bardeen-Cooper-Schrieffer superconductivity with a superconducting transition temperature (Tc) of 36.0 ± 0.5 K for 17.0 ± 1.0 atom % boron concentration. This value is significantly higher than the best experimentally reported Tc of 11 K for crystalline B-doped diamond. We argue that the quenching from metallic carbon liquid leads to a stronger electron-phonon coupling due to close packing of carbon atoms with higher density of states at the Fermi level. With these results, we propose that the non-equilibrium undercooling-assisted synthesis method can be used to fabricate highly doped materials that provide greatly enhanced superconducting properties.

Discovery of High-Temperature Superconductivity (Tc = 55 K) in B-Doped Q-Carbon.

We have achieved a superconducting transition temperature (Tc) of 55 K in 27 at% B-doped Q-carbon. This value represents a significant improvement over previously reported Tc of 36 K in B-doped Q-carbon and is the highest Tc for conventional BCS (Bardeen-Cooper-Schrieffer) superconductivity in bulk carbon-based materials. The B-doped Q-carbon exhibits type-II superconducting characteristics with Hc2(0) ∼ 10.4 T, consistent with the BCS formalism. The B-doped Q-carbon is formed by nanosecond laser melting of B/C multilayered films in a super undercooled state and subsequent quenching. It is determined that ∼67% of the total boron exists with carbon in a sp3 hybridized state, which is responsible for the substantially enhanced Tc. Through the study of the vibrational modes, we deduce that higher density of states near the Fermi level and moderate to strong electron-phonon coupling lead to a high Tc of 55 K. With these results, we establish that heavy B doping in Q-carbon is the pathway for achieving high-temperature superconductivity.