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Electron-Donation for Superconductivity

English title Electron-Donation for Superconductivity
Applicant Chang Johan
Number 179097
Funding scheme SNSF Professorships
Research institution Physik-Institut Universität Zürich
Institution of higher education University of Zurich - ZH
Main discipline Condensed Matter Physics
Start/End 01.01.2019 - 31.12.2020
Approved amount 800'000.00
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Keywords (4)

Quantum Matter; Surface doping; Superconductivity; Two-dimensional electron gasses

Lay Summary (German)

Lead
Superconductivity constitute a fascinating example of a macroscopy quantum matter phase. It’s remarkable properties - dissipationless charge transport and magnetic levitation - hold great potential for future application. In fact, superconductivity is already widely applied for medical scanning devices. Here we propose to complete a new type of condensed matter experimental setup that will allow magneto- surface transport experiment upon doping with alkali ions. This would allow to continuously vary electron carrier concentration on the surface of a material. Typical starting point would be a bulk Mott insulator that upon surface doping can be tuned metallic and potentially superconducting. This approach should accelerate the search for new superconducting phase.
Lay summary

Als Supraleitung bezeichnet man die besondere Eigenschaft gewisser Materialien bei tiefen Temperaturen ihren elektrischen Widerstand komplett zu verlieren. Im Gegensatz zu herkommlichen Leitern wie Kupfer, welche sich beim leiten von Strom erwarmen und daher stets ein Teil der elektrischen Energie als Warme ungenutzt verloren geht, kann Strom mit einem Supraleiter uber beliebige Distanzen vollig verlustfrei ubertragen werden. Allerdings wird der supraleitende Zustand typischerweise nur bei sehr tiefen Temperaturen von etwa -200 Celsius erreicht. Wahrend der letzten 30 Jahre wurden aber stetig neue Materialfamilien entdeckt, die bei immer hoheren Temperaturen supraleitend sind. Fur das technologisch relevante Ziel eines Materials, dass selbst bei Normaltemperatur (ca. 25 Celsius) supraleitet, bedarf es allerdings noch weitgehenden Untersuchungen in die grundlegenden Eigenschaften dieser faszinierenden Verbindungen, deren Verhalten nur mit Hilfe der Quantenphysik erklart werden kann.

Zu diesem Zwecke konstruieren wir eine einzigartige Messapparatur mit der sich die elektrische Leitfahigkeit unter streng kontrollierten, variierbaren Bedingungen untersuchen lasst. So werden wir zum Beispiel eine bestimmte Menge von Ionen auf den Ober achen von Verbindungen deponieren konnen, um deren Elektronenkonzentration kontinuierlich zu verandern und deren Ein uss auf die Leitfahigkeit direkt zu messen. Ausserdem wird die Moglichkeit gescha en die Versuchsobjekte Magnetfeldern variabler Starke und Richtung auszusetzen und so eine weitere Dimension des Problems greifbar zu machen. Mit Hilfe dieser Variablen konnen wir die Ubergange von relativ normalen zu ausserst exotischen Zustanden der Materie genaustens verfolgen – und dies auf einer Zeitskala von wenigen Tagen. Vergleichbare Untersuchungen benotigen, aufgrund der Notwendigkeit fur jede gewunschte Elektronenkonzentration einen separaten Kristall zu zuchten, konventionellerweise Monate oder gar Jahre.

Diese neue, nach modernsten Massstaben konstruierte Apparatur soll also verwendet werden um verschiedenste Supraleiter und verwandte Materialien unter diversen Aspekten zu beleuchten und insgesamt das Verstandnis fur dieses faszinierende und technologisch vielversprechende Phanomen zu erhohen.

Direct link to Lay Summary Last update: 21.11.2018

Responsible applicant and co-applicants

Employees

Publications

Publication
Magnetotransport of dirty-limit van Hove singularity quasiparticles.
(2021), Magnetotransport of dirty-limit van Hove singularity quasiparticles., in Commun Phys, 4, 1.
Crossover from multiple- to single-gap superconductivity in Nb 5 Ir 3 − x Pt x O alloys
(2020), Crossover from multiple- to single-gap superconductivity in Nb 5 Ir 3 − x Pt x O alloys, in Physical Review B, 101, 134513.
Unconventional transverse transport above and below the magnetic transition temperature in Weyl semimetal EuCd2As2
, Unconventional transverse transport above and below the magnetic transition temperature in Weyl semimetal EuCd2As2, in Physical Review Letters, 1.

Collaboration

Group / person Country
Types of collaboration
University of Zurich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Hokkaido university Japan (Asia)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
CNR-SPIN, I-84084 Fisciano, Salerno Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Rutherford Laboratory Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Webinar Individual talk Squeezing the cuprate high-temperature superconductivity problem 16.10.2020 Bristol (via remote), Great Britain and Northern Ireland Chang Johan;
Seminar - Diamond Light Source Individual talk Superconductivity with Strong and Fragile Flavors 05.02.2020 Oxford, Great Britain and Northern Ireland Chang Johan;
Department seminar Individual talk Superconductivity with Strong and Fragile Flavors 10.09.2019 Geneva, Switzerland Chang Johan;
Scientific Cafe Individual talk Superconductivity and Quantum Matter 23.08.2019 Zurich, Switzerland Chang Johan;
SNS conference Talk given at a conference Strain-Engineering Mott-Insulating La2CuO4 16.06.2019 Tokyo, Japan Chang Johan;
Research Frontier of Advanced Spectroscopies for Correlated Electron Systems Talk given at a conference Engineering the Mott State for High-Tc Superconductivity 13.06.2019 Sendai, Japan Chang Johan;
Danscatt-meeting Talk given at a conference Physics and protein diffraction end-station at the SwissFEL 23.05.2019 Aarhus, Denmark Chang Johan;
Department Seminar Individual talk From Mott physics to high-temperature superconductivity 18.04.2019 Seoul , Korean Republic (South Korea) Chang Johan;


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Superconductivity and Quantum Matter German-speaking Switzerland 2019

Associated projects

Number Title Start Funding scheme
160765 Mott Physics Beyond the Heisenberg Model in Iridates and Related Materials 01.01.2016 Sinergia
183330 CristallinaXTREME: X-ray Diffraction under Extreme Conditions 01.11.2019 R'EQUIP
183304 Microwaves for coherent control of quantum matter and magnonic devices 01.12.2018 R'EQUIP
150573 Fluctuations of boson and fermion condensates 01.01.2015 SNSF Professorships
155873 Quantum MAny-body Physics in Solids 01.08.2015 SNSF Starting Grants

Abstract

This extension proposal suggests benefitting from a surface magneto-transport setup constructed in the first funding period. We will have the unique capacity to electron-dope quantum matter surfaces and measure its electronic transport properties. The proposal consists of four science cases (subprojects) for which superconductivity is an overarching thread. Typically, experimental starting points are Mott insulators or a weak band-gap semiconductor that by surface doping can be switched metallic or semi-metallic. These new two-dimensional metallic states are going to be explored for superconductivity and exotic pseudogap instabilities. Another starting point is to take a known superconductor and boost its transition temperature by electron doping. The surface doping provides an alternative route to the traditional solid state bulk approach. Within a time-scale of hours/days, it will be possible to explore complete doping phase diagrams that usually would result from months/years of work. Given the novel methodology, we are guaranteed to enter uncharted territory. We thus trust that our research will generate exciting new discoveries.
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