The experimental results of ARPES and STM for monolayer FeSe/STO. (A) Experimental STM topography of the FM rim and the AFM rim of FeSe/STO. The inset shows an atomic resolution STM topography image at the bulk position of the FM rim and the AFM rim, with the upper Se atom arrangement (the crystal orientations are labeled). (B) Theoretical (black lines) and ARPES band structure around the M point. (C) Theoretical 1D band structure of a FeSe/STO ribbon with FM (left) and AFM (right) edges. (D) Theoretical LDOS for fringe and bulk states. (E) Experimental STS spectra of edge and bulk states for FM (left) and AFM (right) edges. The light blue band in (A)–(D) indicates the SOC distance. (A)–(E) Adapted with permission from Springer Nature. Credit: Matter (2022). DOI: 10.116/j.matt.2022.04.021
A new multi-node FLEET review, published in Matterinvestigates the search for Majorana fermions in iron-based superconductors.
The elusive Majorana fermion, or “angel particle,” proposed by Ettore Majorana in 1937, behaves simultaneously like a particle and an antiparticle — remaining surprisingly stable rather than being self-destructive.
Majorana fermions promise information and communication Technology of zero resistancetackling the rising energy consumption of modern electronics (already 8% of global electricity consumption), and promising sustainable future for computer use.
In addition, it is the presence of Majorana zero energy modes in topological superconductors who have turned those exotic quantum materials into the most important candidate materials for realizing topological quantum computers.
The existence of Majorana fermions in condensed matter systems will aid FLEET in the search for future energy-efficient electronic technologies.
The Angel Particle: Both Matter and Antimatter
Fundamental particles such as electrons, protons, neutrons, quarks and neutrinos (called fermions) each have their own antiparticles. An antiparticle has the same mass as its normal partner, but opposite electrical charge and magnetic moment.
Conventional fermions and anti-fermions form matter and antimatter and destroy each other when combined.
“The Majorana fermion is the only exception to this rule, a composite particle that is its own antiparticle,” says corresponding author Prof. Xiaolin Wang (UOW).
Despite the intensive search for Majorana particles, the clue of its existence has been elusive for decades, because its two conflicting properties (i.e., the positive and negative charge) make it neutral and its interactions with the environment are very weak.
Topological superconductors: fertile ground for the angel particle
While the Majorana particle’s existence has yet to be discovered, despite extensive searches in high-energy physics facilities such as CERN, it may exist as a single-particle excitation in condensed matter systems where band topology and superconductivity coexist.
“Over the past two decades, Majorana particles have been reported in many superconductor heterostructures and have demonstrated strong potential in quantum computing applications,” said Dr. Muhammad Nadeem, a FLEET postdoc at UOW.
A few years ago it was reported that a new type of material called iron-based topological superconductors harbors Majorana particles without the fabrication of heterostructures, which is important for application in real devices.
“Our paper discusses the most recent experimental achievements in these materials: how to obtain topological superconductor materials, experimental observation of the topological state, and detection of Majorana null modes,” said first author UOW Ph.D. candidate Lina Sang.
In these systems, quasiparticles can mimic a particular type of Majorana fermion, such as “chiral” Majorana fermion, one that moves along a one-dimensional path, and Majorana “zero mode,” one that remains confined in zero-dimensional space.
Majorana Zero Mode Applications
If such condensed matter systems, which host Majorana fermions, are experimentally accessible and characterized by a simple technique, it would help researchers direct the engineering of energy-efficient technologies whose functionalities are enabled by using unique physical properties. features of Majorana fermions, such as fault-tolerant topological quantum computers and ultra-low energy electronics.
The hosting of Majorana fermions in topological states of matter, topological insulators and Weyl semi-metals will be covered at this month’s major international conference on semiconductor physics (ICPS), to be held in Sydney, Australia.
The IOP 2021 Quantum Materials Roadmap examines the role of intrinsic spin-orbit coupling (SOC) based quantum materials for Majorana mode-based topological devices, laying evidence on the boundary between strong SOC materials and superconductorsas well as in an iron-based superconductor.
Lina Sang et al, Majorana null modes in iron-based superconductors, Matter (2022). DOI: 10.116/j.matt.2022.04.021
Provided by FLEET
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