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Bachmann MD, Nair N, Flicker F, Ilan R, Meng T, Ghimire NJ, Bauer ED, Ronning F, Analytis JG, Moll PJW. Inducing superconductivity in Weyl semimetal microstructures by selective ion sputtering. SCIENCE ADVANCES 2017; 3:e1602983. [PMID: 28560340 PMCID: PMC5443640 DOI: 10.1126/sciadv.1602983] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/22/2017] [Indexed: 05/14/2023]
Abstract
By introducing a superconducting gap in Weyl or Dirac semimetals, the superconducting state inherits the nontrivial topology of their electronic structure. As a result, Weyl superconductors are expected to host exotic phenomena, such as nonzero-momentum pairing due to their chiral node structure, or zero-energy Majorana modes at the surface. These are of fundamental interest to improve our understanding of correlated topological systems, and, moreover, practical applications in phase-coherent devices and quantum applications have been proposed. Proximity-induced superconductivity promises to allow these experiments on nonsuperconducting Weyl semimetals. We show a new route to reliably fabricate superconducting microstructures from the nonsuperconducting Weyl semimetal NbAs under ion irradiation. The significant difference in the surface binding energy of Nb and As leads to a natural enrichment of Nb at the surface during ion milling, forming a superconducting surface layer (Tc ~ 3.5 K). Being formed from the target crystal itself, the ideal contact between the superconductor and the bulk may enable an effective gapping of the Weyl nodes in the bulk because of the proximity effect. Simple ion irradiation may thus serve as a powerful tool for the fabrication of topological quantum devices from monoarsenides, even on an industrial scale.
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Affiliation(s)
- Maja D. Bachmann
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, U.K
| | - Nityan Nair
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Felix Flicker
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Roni Ilan
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tobias Meng
- Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany
| | | | - Eric D. Bauer
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Filip Ronning
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - James G. Analytis
- Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Philip J. W. Moll
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Corresponding author.
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Crystal growth of Dirac semimetal ZrSiS with high magnetoresistance and mobility. Sci Rep 2017; 7:40603. [PMID: 28098209 PMCID: PMC5241817 DOI: 10.1038/srep40603] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 12/06/2016] [Indexed: 11/09/2022] Open
Abstract
High quality single crystal ZrSiS as a theoretically predicted Dirac semimetal has been grown successfully using a vapor phase transport method. The single crystals of tetragonal structure are easy to cleave into perfect square-shaped pieces due to the van der Waals bonding between the sulfur atoms of the quintuple layers. Physical property measurement results including resistivity, Hall coefficient (RH), and specific heat are reported. The transport and thermodynamic properties suggest a Fermi liquid behavior with two Fermi pockets at low temperatures. At T = 3 K and magnetic field of Hǁc up to 9 Tesla, large magneto-resistance up to 8500% and 7200% for Iǁ(100) and Iǁ(110) were found. Shubnikov de Haas (SdH) oscillations were identified from the resistivity data, revealing the existence of two Fermi pockets at the Fermi level via the fast Fourier transform (FFT) analysis. The Hall coefficient (RH) showed hole-dominated carriers with a high mobility of 3.05 × 104 cm2V−1s−1 at 3 K. ZrSiS has been confirmed to be a Dirac semimetal by the Dirac cone mapping near the X-point via angle resolved photoemission spectroscopy (ARPES) with a Dirac nodal line near the Fermi level identified using scanning tunneling spectroscopy (STS).
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