<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body dir="auto"><div dir="auto">Fysiikan kollokvio huomenna!</div><div dir="auto"><br></div><div dir="auto">Antero Voutilainen</div><div dir="auto">Fyysikkokerho, pj</div><div><br></div><div align="left" dir="auto" style="font-size:100%;color:#000000"><div>-------- Alkuperäinen viesti --------</div><div>Lähettäjä: Tero Tapio Heikkilä <tero.t.heikkila@jyu.fi> </div><div>Päivämäärä: 26.10.2023 12.34 (GMT+02:00) </div><div>Saaja: jyflstaff@korppi.jyu.fi, "Heinosaari, Teiko" <teiko.heinosaari@jyu.fi>, Antero Voutilainen <puheenjohtaja@jyfk.fi> </div><div>Aihe: Tomorrow: Päivi Törmä: Flat band superconductivity, in the physics colloquium </div><div><br></div></div>
Welcome to the University of Jyväskylä physics colloquium. <br>
<div class="moz-forward-container">
<p> On Friday 27th October at 10 am in FYS1 and <a href="https://jyufi.zoom.us/j/66703175507">Zoom</a> (passcode 890524):</p>
<p><b>Päivi Törmä</b> (Aalto University):</p>
<p><i>Flat-band superconductivity</i></p>
<font size="2">We have found that superconductivity and
superfluidity have a connection to quantum geometry [1,2].
Namely, the superfluid weight in a multiband system has a
previously unnoticed component which we call the geometric
contribution. It is proportional to the minimal quantum metric
of the band. Quantum metric is connected to the Berry curvature,
and this allows us to relate superconductivity with the
topological properties of the band. Using this theory, we have
shown that superconductivity is possible also in a flat band
where individual electrons would not move. We and other groups
have shown [3,4] that these results may be essential in
explaining the observation of superconductivity in twisted
bilayer graphene and may eventually help realize superconductors
at elevated temperatures, all the way up to room temperature. In
addition to the promise of high critical temperatures and strong
correlation effects, also the quantum transport in flat band
shows unique behavior [5]: while supercurrent can flow,
quasiparticle transport is highly suppressed even in
non-equilibrium conditions. This may have important consequences
for superconducting devices.<br>
<br>
[1] S. Peotta, P. Törmä, Nature Commun. 6, 8944 (2015); A.
Julku, S. Peotta, T.I. Vanhala, D.-H. Kim, P. Törmä, Phys. Rev.
Lett. 117, 045303 (2016); P. Törmä, L. Liang, S. Peotta, Phys.
Rev. B 98, 220511(R) (2018).<br>
[2] K.-E. Huhtinen, J. Herzog-Arbeitman, A. Chew, B.A. Bernevig,
P. Törmä, Phys. Rev. B 106 , 014518 (2022); J. Herzog-Arbeitman,
A. Chew, K.-E. Huhtinen, P. Törmä, B.A. Bernevig,
arXiv:2209.00007 (2022).<br>
[3] A. Julku, T.J. Peltonen, L. Liang, T.T. Heikkilä, P. Törmä,
Phys. Rev. B 101, 060505(R) (2020); X. Hu, T. Hyart, D.I.
Pikulin, E. Rossi, Phys. Rev. Lett. 123, 237002 (2019); F. Xie,
Z. Song, B. Lian, B.A. Bernevig, Phys. Rev. Lett. 124, 167002
(2020).<br>
[4] P. Törmä, S. Peotta, B.A. Bernevig, Nat. Rev. Phys. 4, 528
(2022).<br>
[5] V.A.J. Pyykkönen, S. Peotta, P. Törmä, Phys. Rev. Lett. 130,
216003 (2023).</font><br>
<p>Welcome!</p>
<p> Coffee will be served in the lobby. Although on-site
attendance is the preferred option, you can also join via Zoom.
Please do not send chat messages in Zoom during the talk, except
if you need to tell about a muted speaker. <br>
</p>
<p>Confirmed colloquium talks in the Fall 2023 (you are welcome to
suggest more - there are still open slots):<br>
3.11. Mathias Kläui (Mainz): <i>Antiferromagnetic Spintronics:
Spintronics without magnetic fields</i><br>
10.11. Andreas Norman (UEF): <i>Quantum complementarities in
vectorial light fields<br>
</i>17.11. Thomas Cocolios (KU Leuven): <i>Novel radionuclides
for medical applications: from the nuclear lab to patients</i></p>
<p>Tero & Iain<br>
</p>
<pre cols="72" class="moz-signature">--
Tero Heikkilä
Professor, Department of Physics
University of Jyväskylä</pre>
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