News

Superconducting switch from a nanowire

2021. November 23.

Novel gate-tunable superconductor-based circuit element created and studied by the BME Quantum Electronics Research Group. Publication in Nano Letters.

 

Tosson Elalaily, Olivér Kürtössy, Zoltán Scherübl, Martin Berke, Gergö Fülöp, István Endre Lukács, Thomas Kanne, Jesper Nygård, Kenji Watanabe, Takashi Taniguchi, Péter Makk, and Szabolcs Csonka
Gate-Controlled Supercurrent in Epitaxial Al/InAs Nanowires
Nano Letters (2021)
 
Link: 
https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.1c03493

Kondo cloud in superconductors

2021. November 10.

New theory results from BME on the electronic states forming around magnetic impurities in superconductors. Published as Editor's Suggestion in Physical Review Letters, and featured as a Synopsis in APS Physics.

 
Cătălin Paşcu Moca, Ireneusz Weymann, Miklós Antal Werner, and Gergely Zaránd
Kondo Cloud in a Superconductor
Phys. Rev. Lett. 127, 186804 – Published 27 October 2021
https://doi.org/10.1103/PhysRevLett.127.186804
 
 
 
Link: 
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.186804

Electromechanics in graphene

2021. November 02.

How and why does the resistance of a graphene nanostructure change, when placed in a pressure cell?

 

Researchers of the BME Quantum Electronics group, along with colleagues at ETH Zürich, address this question in their recent experiment. Two bilayer graphene flakes are pushed against each other in a twisted fashion, akin to recent breakthrough experiments discovering superconductivity in similar samples. The team measured the resistance of the nanostructure as function of pressure and temperature; this allowed to infer key features of the electronic band structure as well. The results are publised in Nano Letters. 

 

Bálint Szentpéteri, Peter Rickhaus, Folkert K. de Vries, Albin Márffy, Bálint Fülöp, Endre Tóvári, Kenji Watanabe, Takashi Taniguchi, Andor Kormányos, Szabolcs Csonka, and Péter Makk
Tailoring the Band Structure of Twisted Double Bilayer Graphene with Pressure
Nano Lett. 2021, 21, 20, 8777 (2021)
https://doi.org/10.1021/acs.nanolett.1c03066

 

Link: 
https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.1c03066

Electric control of an optical diode

2021. October 17.

Electrically controlled optical diode mechanism in a magnetoelectric crystal was discovered by the BME Complex Magnetic Structures research group. Published in Physical Review Letters.

 

The research group, leading an international collaboration, has studied the optical properties of a magnetoelectric antiferromagnet (Ba2CoGe2O7) in the terahertz frequency range. They found a optical diode effect, also known as non-reciprocal light absorption, meaning that a crystal absorbs the electromagnetic radiation for a given propagation direction but transmits most of the light for the counterpropagating radiation. The BME researchers could control the optical diode effect by electric fields. This study also revealed that tuning the electric field can switch the state of the antiferromagnetic domains of the sample, and this is the mechanism that allows for an electrical control of the optical diode effect. These results might enable the design of light switches in the terahertz domain based on antiferromagnets similar to Ba2CoGe2O7.

 

J. Vít, J. Viirok, L. Peedu, T. Rõõm, U. Nagel, V. Kocsis, Y. Tokunaga, Y. Taguchi, Y. Tokura, I. Kézsmárki, P. Balla, K. Penc, J. Romhányi, and S. Bordács
In Situ Electric-Field Control of THz Nonreciprocal Directional Dichroism in the Multiferroic Ba2CoGe2O7
Phys. Rev. Lett. 127, 157201 (2021)
https://doi.org/10.1103/PhysRevLett.127.157201
Link: 
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.127.157201

Control of spin-orbit coupling in graphene

2021. October 11.

New experiment from BME Quantum Electronics Research Group demonstrates mechanical control of spin-orbit coupling in graphene. In: npj 2D materials and applications. 

 

BME Quantum Electronics Research Group: https://nanoelectronics.physics.bme.hu/Quantum_intro

 

Bálint Fülöp, Albin Márffy, Simon Zihlmann, Martin Gmitra, Endre Tóvári, Bálint Szentpéteri, Máté Kedves, Kenji Watanabe, Takashi Taniguchi, Jaroslav Fabian, Christian Schönenberger, Péter Makk & Szabolcs Csonka 
Boosting proximity spin–orbit coupling in graphene/WSe2 heterostructures via hydrostatic pressure
npj 2D Materials and Applications volume 5, Article number: 82 (2021)
https://doi.org/10.1038/s41699-021-00262-9

 

 

Link: 
https://www.nature.com/articles/s41699-021-00262-9

Andreev molecule in Nano Letters

2021. September 26.

Our colleagues at the BME Department of Physics created a novel artificial molecule in nano-sized electronic circuits, at extremely low temperatures. In natural molecules, electrons can tunnel between neighboring atoms. In this new, artificial, so-called Andreev molecule, the artificial atoms are cca. 1000-times larger than natural atoms, and the tunneling of electrons happens via a superconducting electrode. Interestingly, the superconducting electrode can absorb and re-emit pairs of electrons from and to the molecule This is a feature absent in usual molecules, altering the energy spectrum which was now measured by the BME researchers for the first time. The artificial atoms of the Andreev molecule are created in semiconducting nanowires from the group of Prof. Jesper Nygard (University of Copenhagen). This newly demonstrated artificial molecule is an important step in the development of long-lived quantum bits. 

 

Olivér Kürtössy, Zoltán Scherübl, Gergö Fülöp, István Endre Lukács, Thomas Kanne, Jesper Nygård, Péter Makk, and Szabolcs Csonka
Andreev Molecule in Parallel InAs Nanowires
Nano Letters, 2021
Link: 
https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.1c01956

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