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Ultrathin Semiconductors Equipped With Superconducting Contacts for the First Time

The monolayer of molybdenum disulfide (MoS2) is sandwiched between two protecting layers of boron nitride (hBN), with molybdenum rhenium (MoRe) contacts extending by way of the higher one. A layer of graphene (gate) is used for electrical management. Credit score: Mehdi Ramezani, Swiss Nanoscience Institute, College of Basel

For the first time, College of Basel researchers have geared up an ultrathin semiconductor with superconducting contacts. These extraordinarily skinny supplies with novel digital and optical properties might pave the approach for beforehand unimagined functions. Mixed with superconductors, they’re anticipated to offer rise to new quantum phenomena and discover use in quantum know-how.

Whether or not in smartphones, televisions or constructing know-how, semiconductors play a central position in electronics and subsequently in our on a regular basis lives. In distinction to metals, it’s attainable to regulate their electrical conductivity by making use of a voltage and therefore to change the present move on and off.

With a view to future functions in electronics and quantum know-how, researchers are specializing in the growth of latest elements that encompass a single layer (monolayer) of a semiconducting materials. Some naturally occurring supplies with semiconducting properties characteristic monolayers of this sort, stacked to kind a three-dimensional crystal. In the laboratory, researchers can separate these layers – which are not any thicker than a single molecule – and use them to construct digital elements.

These ultrathin semiconductors promise to ship distinctive traits which are in any other case very troublesome to regulate, resembling the use of electrical fields to affect the magnetic moments of the electrons. As well as, advanced quantum mechanical phenomena happen in these semiconducting monolayers which will have functions in quantum know-how.

For the first time, SNI researchers (College of Basel) have geared up an atomically skinny semiconductor with superconducting contacts. On this video, they present the elaborate fabrication course of. Credit score: C. Möller and M. Ramezani, Swiss Nanoscience Institute, College of Basel

Scientists worldwide are investigating how these skinny semiconductors could be stacked to kind new artificial supplies, often known as van der Waals heterostructures. Nevertheless, till now, they haven’t succeeded in combining such a monolayer with superconducting contacts to be able to dig deeper into the properties and peculiarities of the new supplies.

A crew of physicists, led by Dr. Andreas Baumgartner in the analysis group of Professor Christian Schönenberger at the Swiss Nanoscience Institute and the Division of Physics of the College of Basel, has now fitted a monolayer of the semiconductor molybdenum disulfide with superconducting contacts for the first time. (see field)

The rationale why this mix of semiconductor and superconductor is so fascinating is that the specialists anticipate elements of this sort to exhibit new properties and bodily phenomena. “In a superconductor, the electrons organize themselves into pairs, like companions in a dance – with strange penalties, resembling the move of the electrical present and not using a resistance,” explains Baumgartner, the mission supervisor of the examine. “In the semiconductor molybdenum disulfide, on the different hand, the electrons carry out a totally completely different dance, a wierd solo routine that additionally incorporates their magnetic moments. Now we want to discover out which new and unique dances the electrons agree upon if we mix these supplies.”

{The electrical} measurements at the low temperatures required for superconductivity – simply above absolute zero (-273.15°C) – present clearly the results attributable to the superconductor; for instance, at sure energies, single electrons are not allowed. Furthermore, the researchers discovered indications of a powerful coupling between the semiconductor layer and the superconductor.

“Sturdy coupling is a key factor in the new and thrilling bodily phenomena that we anticipate to see in such van der Waals heterostructures, however have been by no means capable of display,” says Mehdi Ramezani, lead writer of the examine.

“And, after all, we at all times hope for new functions in electronics and quantum know-how,” says Baumgartner. “In precept, the vertical contacts we’ve developed for the semiconductor layers could be utilized to numerous semiconductors. Our measurements present that these hybrid monolayer semiconductor elements are certainly attainable –even perhaps with different, extra unique contact supplies that may pave the approach for additional insights,” he provides.

Reference: “Superconducting Contacts to a Monolayer Semiconductor” by Mehdi Ramezani, Ian Correa Sampaio, Kenji Watanabe, Takashi Taniguchi, Christian Schönenberger and Andreas Baumgartner, 23 June 2021, Nano Letters.
DOI: 10.1021/acs.nanolett.1c00615

Funding: Swiss NationalScience Basis, Swiss Nanoscience Institute (SNI) mission P1701, and theERC mission High-Supra (787414)

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