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Adv. Quantum Technol. 2400476 (2024)
Superconducting nanowires underpin the development of a variety of advanced quantum devices. In 1D superconducting nanowires, topological fluctuations of the superconducting order parameter, known as phase slips, influence the electrical transport severely. In 3D systems, however, phase-slip events are generally considered to be insignificant. This research provides the first evidence that quantum phase slips can also play a crucial role in 3D superconducting nanowires, e.g., giving rise to a reentrant resistive state.
Adv. Funct. Mater. 2415109 (2024)
Surface metallization of diamond with transition metals (TMs) is crucial to the development of precision machining, high-end thermal management, and advanced electronic devices. The microscopic mechanism of the interfacial reaction between diamond and TMs, however, remains elusive. Our research on monocrystalline intrinsic diamond metalized with Ti/Pt/Au ohmic contacts shows that upon annealing, TM atoms can diffuse deep into diamond, aggregate into nanoclusters, and exacerbate the amorphization of diamond.
Phys. Rev. Mater. 8, 044802 (2024)
Despite its great promise for opening up new paradigms in the semiconductor industry and quantum electronics, diamond has a rather low heat tolerance. Annealing beyond 600 °C can induce severe local amorphization in a diamond thin film and transform it into a binary mixture of spatially separate domains of amorphous carbon and diamond grains, which causes severe degradation of the electronic performance of this material. This has serious implications for the use of diamond in high-temperature electronic applications.
Adv. Mater. 35, 2211129 (2023)
Nanoscale ‘diamond rings’ provide unconventional giant ‘magnetoresistance’ for the development of new quantum devices. The unconventional giant ‘magnetoresistance’, caused by the trapping of Cooper pairs within the heavily boron-doped diamond nanorings, distinguishes itself from the conventional giant magnetoresistance originating from spin-dependent scattering of single electrons in layered magnetic materials.
When magnetic impurities are introduced into a superconductor, the magnetic moments will destroy the local superconductivity, giving rise to Yu-Shiba-Rusinov (YSR) states in the superconducting gap. Such YSR states are generally localized within a few atomic sizes. Our discovery of YSR bands with a spatial extent of tens of nanometers in hydrogenated boron-doped nanodiamond films, opens the door to interfacing exotic electronic excitations with nanoelectronics for quantum computing.
Adv. Mater. 32, 2002352 (2020)
Crystalline and amorphous structures are two of the most common solid-state phases. The combination of short-range disordered and long-range ordered structures at the atomic level is extremely rare. By compressing a linear chain compound under high pressures, we created a system with long-range ordered but short-range disordered building blocks. Our findings demonstrate a first ever case where superconductivity is hosted by a lattice with periodic but amorphous constituent atomic chains.
Phys. Rev. Appl. 12, 064042 (2019)
In contrast to other superconducting thin films featuring a larger in-plane upper critical field, nanodiamond films show a larger out-of-plane upper critical field, due to quantum confinement effects induced by crystallite geometry. This study provides physical insight for developing nanodiamond-based superconducting quantum devices, by exploiting grain or twin boundaries.
Phys. Rev. Mater. 3, 034801 (2019)
High-pressure techniques have been commonly used to study the electronic structures of condensed matter, whereas we use the technique as an efficient tool to tune the intergrain coupling in nanodiamond thin films. This work unveils the percolative nature of the electrical transport in nanodiamond films and highlight the essential role of grain boundaries in determining the electronic properties of this material.
Water electrolysis shows great promise for low-cost mass production of high-purity hydrogen. As a clean and renewable fuel, the widespread use of hydrogen will significantly reduce emissions of greenhouse gas and other pollutants. Using the hybrids of PtRu nanoclusters and black phosphorus nanosheets, we increase the efficiency of water electrolysis by one order of magnitude in contrast to that of commercial electrocatalysts.
A long-standing question was whether the route to insulating behavior proceeds through the direct localization of Cooper pairs or, alternatively, by a two-step process in which the Cooper pairing is first destroyed followed by the localization of single electrons. Here, we address this question by studying the superconductor-bosonic insulator transition in nanodiamond arrays as a function of the dispersion of intergrain spacing.
Superconductivity and ferromagnetism are two mutually antagonistic states, and their coexistence is very rare in nature. This study unveils the coexistent superconductivity and ferromagnetism in hydrogenated boron-doped nanodiamond films. The observed high-temperature ferromagnetism, giant magnetoresistance, and anomalous Hall effect pave the path towards the applications of the nanodiamond films in magnetoelectronics.
Phys. Rev. Appl. 6, 064011 (2016)
Quantum confinement is considered the cause of many intriguing features for systems which are generally low dimensional, strongly disordered, and/or situated in the vicinity of the metal-insulator transition. Our work reveals that despite its three-dimensional, weakly disordered and metallic nature, polycrystalline bulk diamond still demonstrates strong quantum confinement effects as shown in its anomalous electronic properties.
Superconducting nanowires attract great interest due to their applications in single-photon detectors and quantum-computing circuits. We use controlled electromigration to narrow down aluminium nanoconstrictions. When the cross section becomes less than ∼150 nm2, a transition from thermally assisted phase slips to quantum phase slips takes place in the aluminium nanowires.
The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. To address this issue, we dope iron pnictide with substitutional non-magnetic impurities. Our data provide evidence for the pair-breaking effect of non-magnetic impurities and the unconventional s± pairing symmetry for the iron pnictide superconductors.
Strong granularity‐correlated and intragrain modulations of the superconducting order parameter are demonstrated in heavily boron‐doped diamond situated not yet in the vicinity of the metal‐insulator transition. These modulations at the superconducting state and at the global normal state above the resistive superconducting transition, reveal that local Cooper pairing sets in prior to the global phase coherence.
Phys. Rev. Lett. 110, 077001 (2013)
In a variety of superconductors, the resistive superconducting transition demonstrates an anomalous narrow peak just preceding the onset of the superconducting state. The origin of such peaks had remained an open question for decades. Here, we report on our observation of a giant resistance peak in granular diamond, which is interpreted as metal – bosonic insulator – superconductor transitions.
Phys. Rev. B 84, 214517 (2011)
Synthetic diamond in the form of thin film offers opportunities of printing diamond circuitry and shaping the material into other high-tech devices, e.g. diamond microchips or even superchips. As a result of the synthetic method, diamond thin films generally show a nanogranular morphology. This research provides physical insight for the influence of the nanoscale granularity on the electronic properties of nanodiamond films.
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