scholarly journals Zero-energy bound states in the high-temperature superconductors at the two-dimensional limit

2020 ◽  
Vol 6 (13) ◽  
pp. eaax7547 ◽  
Author(s):  
Chaofei Liu ◽  
Cheng Chen ◽  
Xiaoqiang Liu ◽  
Ziqiao Wang ◽  
Yi Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Bound States ◽  
High Temperature Superconductors ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Zero Energy ◽  
Topological Superconductors ◽  
Topological Quantum ◽  
Energy Bound

Majorana zero modes (MZMs) that obey the non-Abelian statistics have been intensively investigated for potential applications in topological quantum computing. The prevailing signals in tunneling experiments “fingerprinting” the existence of MZMs are the zero-energy bound states (ZEBSs). However, nearly all of the previously reported ZEBSs showing signatures of the MZMs are observed in difficult-to-fabricate heterostructures at very low temperatures and additionally require applied magnetic field. Here, by using in situ scanning tunneling spectroscopy, we detect the ZEBSs upon the interstitial Fe adatoms deposited on two different high-temperature superconducting one-unit-cell iron chalcogenides on SrTiO3(001). The spectroscopic results resemble the phenomenological characteristics of the MZMs inside the vortex cores of topological superconductors. Our experimental findings may extend the MZM explorations in connate topological superconductors toward an applicable temperature regime and down to the two-dimensional (2D) limit.

scholarly journals Nearly quantized conductance plateau of vortex zero mode in an iron-based superconductor

Science ◽  
2019 ◽  
pp. eaax0274 ◽  
Author(s):  
Shiyu Zhu ◽  
Lingyuan Kong ◽  
Lu Cao ◽  
Hui Chen ◽  
Michał Papaj ◽  
...  
Keyword(s):  
Bound States ◽  
Zero Mode ◽  
Finite Energy ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Tunneling Conductance ◽  
Zero Energy ◽  
Tunnel Coupling ◽  
Topological Quantum ◽  
The Continuum

Majorana zero modes (MZMs) are spatially-localized zero-energy fractional quasiparticles with non-Abelian braiding statistics that hold promise for topological quantum computing. Owing to the particle-antiparticle equivalence, MZMs exhibit quantized conductance at low temperature. By utilizing variable-tunnel-coupled scanning tunneling spectroscopy, we study tunneling conductance of vortex bound states on FeTe0.55Se0.45 superconductors. We report observations of conductance plateaus as a function of tunnel coupling for zero-energy vortex bound states with values close to or even reaching the 2e2/h quantum conductance (here e is the electron charge and h is Planck’s constant). In contrast, no plateaus were observed on either finite energy vortex bound states or in the continuum of electronic states outside the superconducting gap. This behavior of the zero-mode conductance supports the existence of MZMs in FeTe0.55Se0.45.

scholarly journals Scanning tunneling spectroscopy of high-temperature superconductors

2007 ◽  
Vol 79 (1) ◽  
pp. 353-419 ◽  
Author(s):  
Øystein Fischer ◽  
Martin Kugler ◽  
Ivan Maggio-Aprile ◽  
Christophe Berthod ◽  
Christoph Renner
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling

scholarly journals Evidence for Majorana bound states in an iron-based superconductor

Science ◽  
2018 ◽  
Vol 362 (6412) ◽  
pp. 333-335 ◽  
Author(s):  
Dongfei Wang ◽  
Lingyuan Kong ◽  
Peng Fan ◽  
Hui Chen ◽  
Shiyu Zhu ◽  
...  
Keyword(s):  
Bound States ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Vortex Center ◽  
Zero Energy ◽  
Zero Bias ◽  
Majorana Bound States ◽  
Topological Materials ◽  
Field Temperature ◽  
Iron Based

The search for Majorana bound states (MBSs) has been fueled by the prospect of using their non-Abelian statistics for robust quantum computation. Two-dimensional superconducting topological materials have been predicted to host MBSs as zero-energy modes in vortex cores. By using scanning tunneling spectroscopy on the superconducting Dirac surface state of the iron-based superconductor FeTe0.55Se0.45, we observed a sharp zero-bias peak inside a vortex core that does not split when moving away from the vortex center. The evolution of the peak under varying magnetic field, temperature, and tunneling barrier is consistent with the tunneling to a nearly pure MBS, separated from nontopological bound states. This observation offers a potential platform for realizing and manipulating MBSs at a relatively high temperature.

scholarly journals Controlling in-gap end states by linking nonmagnetic atoms and artificially-constructed spin chains on superconductors

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Lucas Schneider ◽  
Sascha Brinker ◽  
Manuel Steinbrecher ◽  
Jan Hermenau ◽  
Thore Posske ◽  
...  
Keyword(s):  
Bound States ◽  
Magnetic Order ◽  
Tight Binding ◽  
Spectral Weight ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Topological Quantum ◽  
Topological Quantum Computation ◽  
Gap States ◽  
Spatial Transition

Abstract Chains of magnetic atoms with either strong spin-orbit coupling or spiral magnetic order which are proximity-coupled to superconducting substrates can host topologically non-trivial Majorana bound states. The experimental signature of these states consists of spectral weight at the Fermi energy which is spatially localized near the ends of the chain. However, topologically trivial Yu-Shiba-Rusinov in-gap states localized near the ends of the chain can lead to similar spectra. Here, we explore a protocol to disentangle these contributions by artificially augmenting a candidate Majorana spin chain with orbitally-compatible nonmagnetic atoms. Combining scanning tunneling spectroscopy with ab-initio and tight-binding calculations, we realize a sharp spatial transition between the proximity-coupled spiral magnetic order and the non-magnetic superconducting wire termination, with persistent zero-energy spectral weight localized at either end of the magnetic spiral. Our findings open a new path towards the control of the spatial position of in-gap end states, trivial or Majorana, via different chain terminations, and the realization of designer Majorana chain networks for demonstrating topological quantum computation.

SCANNING TUNNELING MICROSCOPIC STUDY OF THE INTERFACE SUPERCONDUCTIVITY

2018 ◽  
Vol 25 (Supp01) ◽  
pp. 1841001
Author(s):  
YANG WANG ◽  
CAN-LI SONG ◽  
LILI WANG ◽  
XU-CUN MA ◽  
QI-KUN XUE
Keyword(s):  
High Temperature ◽  
Scanning Tunneling Microscope ◽  
Condensed Matter ◽  
High Temperature Superconductors ◽  
Atomic Level ◽  
Scanning Tunneling ◽  
Two Dimensional ◽  
Interface Engineering ◽  
Tunneling Microscope ◽  
Interface Superconductivity

It has been 30 years since the Nobel Prize was awarded for scanning tunneling microscope (STM) in the year 1986, and there have been many instrumental developments and experimental achievements based on STM. In consideration of the strong capability and the extreme versatility in imaging, manipulating, and spectroscopy at the atomic level, STM has witnessed remarkable breakthroughs in many disciplines of condensed matter physics. In this paper, we will focus on recent STM studies on the interface superconductivity, which demonstrate a novel platform for exploring two dimensional superconductors and even high temperature superconductors by means of interface engineering.

Particle–hole asymmetry in the scanning tunneling spectroscopy of the high temperature superconductors

2007 ◽  
Vol 244 (7) ◽  
pp. 2448-2452 ◽  
Author(s):  
Anna Gorczyca ◽  
Mariusz Krawiec ◽  
Maciej M. Maśka ◽  
Marcin Mierzejewski
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Scanning Tunneling Spectroscopy ◽  
Tunneling Spectroscopy ◽  
Scanning Tunneling

scholarly journals Topological superconductivity in skyrmion lattices

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Eric Mascot ◽  
Jasmin Bedow ◽  
Martin Graham ◽  
Stephan Rachel ◽  
Dirk K. Morr
Keyword(s):  
Complex Structure ◽  
Magnetic Layer ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Topological Superconductors ◽  
And Topology ◽  
Topological Quantum ◽  
Spin Triplet ◽  
Atomic Manipulation ◽  
Topological Superconductivity

AbstractAtomic manipulation and interface engineering techniques have provided an intriguing approach to custom-designing topological superconductors and the ensuing Majorana zero modes, representing a paradigm for the realization of topological quantum computing and topology-based devices. Magnet-superconductor hybrid (MSH) systems have proven to be experimentally suitable to engineer topological superconductivity through the control of both the complex structure of its magnetic layer and the interface properties of the superconducting surface. Here, we demonstrate that two-dimensional MSH systems containing a magnetic skyrmion lattice provide an unprecedented ability to control the emergence of topological phases. By changing the skyrmion radius, which can be achieved experimentally through an external magnetic field, one can tune between different topological superconducting phases, allowing one to explore their unique properties and the transitions between them. In these MSH systems, Josephson scanning tunneling spectroscopy spatially visualizes one of the most crucial aspects underlying the emergence of topological superconductivity, the spatial structure of the induced spin–triplet correlations.

scholarly journals Assessing Bound States in a One-Dimensional Topological Superconductor: Majorana versus Tamm

2021 ◽  
Author(s):  
Niccolò Traverso Ziani ◽  
Lucia Vigliotti ◽  
Matteo Carrega ◽  
Fabio Cavaliere
Keyword(s):  
Quantum Computation ◽  
Bound States ◽  
Research Activity ◽  
One Dimensional ◽  
Majorana Bound States ◽  
Topological Superconductors ◽  
Topological Quantum ◽  
Tamm State ◽  
Topological Quantum Computation ◽  
Intense Research

Majorana bound states in topological superconductors have attracted intense research activity in view of applications in topological quantum computation. However, they are not the only example of topological bound states that can occur in such systems. We here study a model in which both Majorana and Tamm bound states compete. We show both numerically and analytically that, surprisingly, the Tamm state remains partially localized even when the spectrum becomes gapless. Despite this fact, we demonstrate that the Majorana polarization shows a clear transition between the two regimes.

scholarly journals Spectral singularities and zero energy bound states

2011 ◽  
Vol 63 (3) ◽  
pp. 369-373 ◽  
Author(s):  
W. D. Heiss ◽  
R. G. Nazmitdinov
Keyword(s):  
Bound States ◽  
Zero Energy ◽  
Spectral Singularities ◽  
Energy Bound
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