Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor

Ritesh Sachan; Jordan A. Hachtel; Anagh Bhaumik; Adele Moatti; John Prater; Juan Carlos Idrobo; Jagdish Narayan

doi:10.1016/j.actamat.2019.05.013

Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor

Ritesh Sachan, Jordan A. Hachtel, Anagh Bhaumik, Adele Moatti, John Prater, Juan Carlos Idrobo, Jagdish Narayan

electron Microscopy and Microanalysis

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

We report the spectroscopic demonstration of the shallow-level energy states in the recently discovered B-doped Q-carbon Bardeen-Cooper-Schrieffer (BCS)high-temperature superconductor. The Q-carbon is synthesized by ultrafast melting and quenching, allowing for high B-doping concentrations which increase the superconducting transition temperature (T_c)to 36 K (compared to 4 K for B-doped diamond). The increase in T_c is attributed to the increased density of energy states near the Fermi level in B-doped Q-carbon, which give rise to superconducting states via strong electron-phonon coupling below T_c. These shallow-level energy states, however, are challenging to map due to limited spatial and energy resolution. Here, we use ultrahigh energy resolution monochromated electron energy-loss spectroscopy (EELS), to detect and visualize the newly formed shallow-level energy states (vibrational modes)near the Fermi level (ranging 30–100 meV)of the B-doped Q-carbon. With this study, we establish the significance of high-resolution EELS in understanding the superconducting behavior of BCS superconducting C-based materials, which demonstrate a phenomenal enhancement in the presence of shallow-level energy states.

Original language	English
Pages (from-to)	153-159
Number of pages	7
Journal	Acta Materialia
Volume	174
DOIs	https://doi.org/10.1016/j.actamat.2019.05.013
State	Published - Aug 1 2019

Funding

We are grateful to Fan Family Foundation Distinguished Chair Endowment for J.R. R.S. acknowledges the National Academy of Sciences, USA for awarding the NRC research fellowship. R.S. and J.P. acknowledge support from ARO Grant No. W911NF-16-2-0038 . This work was performed under the National Science Foundation (Award number DMR-1735695 ). We used the Analytical Instrumentation Facility (AIF) at North Carolina State University , which is supported by the State of North Carolina and the National Science Foundation (Award Number ECCS-1542015 ). A part of this research was supported by the U.S. Department of Energy , Office of Science , Basic Energy Sciences, Materials Science and Technology Division (RS) . The high-resolution electron energy-loss spectroscopy part of this research was conducted at the Center for Nanophase Materials Sciences , which is a Department of Energy , Office of Science User Facility (J.A.H. & J.C.I.). This research was conducted, in part, using instrumentation within ORNL’s Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy . We are grateful to Fan Family Foundation Distinguished Chair Endowment for J.R. R.S. acknowledges the National Academy of Sciences, USA for awarding the NRC research fellowship. R.S. and J.P. acknowledge support from ARO Grant No. W911NF-16-2-0038. This work was performed under the National Science Foundation (Award number DMR-1735695). We used the Analytical Instrumentation Facility (AIF)at North Carolina State University, which is supported by the State of North Carolina and the National Science Foundation (Award Number ECCS-1542015). A part of this research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Technology Division (RS). The high-resolution electron energy-loss spectroscopy part of this research was conducted at the Center for Nanophase Materials Sciences, which is a Department of Energy, Office of Science User Facility (J.A.H. & J.C.I.). This research was conducted, in part, using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy.

Funders	Funder number
Materials Science and Technology Division
UT-Battelle, LLC
National Science Foundation	DMR-1735695
U.S. Department of Energy
Army Research Office	W911NF-16-2-0038
National Academy of Sciences
Office of Science
Basic Energy Sciences
North Carolina State University	ECCS-1542015
National Research Council
National Research Council Canada

Keywords

BCS superconductivity
Carbon
Monochromated electron energy-loss spectroscopy
Q-carbon
Shallow energy levels

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10.1016/j.actamat.2019.05.013

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title = "Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor",

abstract = "We report the spectroscopic demonstration of the shallow-level energy states in the recently discovered B-doped Q-carbon Bardeen-Cooper-Schrieffer (BCS)high-temperature superconductor. The Q-carbon is synthesized by ultrafast melting and quenching, allowing for high B-doping concentrations which increase the superconducting transition temperature (Tc)to 36 K (compared to 4 K for B-doped diamond). The increase in Tc is attributed to the increased density of energy states near the Fermi level in B-doped Q-carbon, which give rise to superconducting states via strong electron-phonon coupling below Tc. These shallow-level energy states, however, are challenging to map due to limited spatial and energy resolution. Here, we use ultrahigh energy resolution monochromated electron energy-loss spectroscopy (EELS), to detect and visualize the newly formed shallow-level energy states (vibrational modes)near the Fermi level (ranging 30–100 meV)of the B-doped Q-carbon. With this study, we establish the significance of high-resolution EELS in understanding the superconducting behavior of BCS superconducting C-based materials, which demonstrate a phenomenal enhancement in the presence of shallow-level energy states.",

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AU - Bhaumik, Anagh

AU - Moatti, Adele

AU - Prater, John

AU - Idrobo, Juan Carlos

AU - Narayan, Jagdish

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N2 - We report the spectroscopic demonstration of the shallow-level energy states in the recently discovered B-doped Q-carbon Bardeen-Cooper-Schrieffer (BCS)high-temperature superconductor. The Q-carbon is synthesized by ultrafast melting and quenching, allowing for high B-doping concentrations which increase the superconducting transition temperature (Tc)to 36 K (compared to 4 K for B-doped diamond). The increase in Tc is attributed to the increased density of energy states near the Fermi level in B-doped Q-carbon, which give rise to superconducting states via strong electron-phonon coupling below Tc. These shallow-level energy states, however, are challenging to map due to limited spatial and energy resolution. Here, we use ultrahigh energy resolution monochromated electron energy-loss spectroscopy (EELS), to detect and visualize the newly formed shallow-level energy states (vibrational modes)near the Fermi level (ranging 30–100 meV)of the B-doped Q-carbon. With this study, we establish the significance of high-resolution EELS in understanding the superconducting behavior of BCS superconducting C-based materials, which demonstrate a phenomenal enhancement in the presence of shallow-level energy states.

AB - We report the spectroscopic demonstration of the shallow-level energy states in the recently discovered B-doped Q-carbon Bardeen-Cooper-Schrieffer (BCS)high-temperature superconductor. The Q-carbon is synthesized by ultrafast melting and quenching, allowing for high B-doping concentrations which increase the superconducting transition temperature (Tc)to 36 K (compared to 4 K for B-doped diamond). The increase in Tc is attributed to the increased density of energy states near the Fermi level in B-doped Q-carbon, which give rise to superconducting states via strong electron-phonon coupling below Tc. These shallow-level energy states, however, are challenging to map due to limited spatial and energy resolution. Here, we use ultrahigh energy resolution monochromated electron energy-loss spectroscopy (EELS), to detect and visualize the newly formed shallow-level energy states (vibrational modes)near the Fermi level (ranging 30–100 meV)of the B-doped Q-carbon. With this study, we establish the significance of high-resolution EELS in understanding the superconducting behavior of BCS superconducting C-based materials, which demonstrate a phenomenal enhancement in the presence of shallow-level energy states.

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Emergence of shallow energy levels in B-doped Q-carbon: A high-temperature superconductor

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