ELFT HÍRADÓ

[Szeminárium koordinátor <szfi-seminar AT wigner.mta.hu>]

SZFI Seminar
Csire Gábor
(Barcelona Institute of Science and Technology)
Unconventional magnetically-textured superconductivity in elemental rhenium 
crystals
When a superconductor is cooled below its critical temperature Tc the phase 
of the electronic wave function gets locked to a particular value. This leads 
to quantum effects on the scale of everyday objects which underpin 
superconducting quantum technologies. In some unconventional superconductors 
this form of symmetry breaking is concomitant with additional breaking of 
time-reversal symmetry (TRS) indicating that the superconducting state is 
intrinsically magnetic. Such systems are expected to have important 
applications in spintronics and topological quantum computing, however this 
is hindered by the lack of a general theory of unconventional 
superconductivity which is normally associated with strong electron 
correlations or fluctuations of competing ordered phases. Recently, however, 
TRS breaking has been reported in seemingly ordinary superconductors where 
such exotic physics are not at play, including the chemical element rhenium. 
Here we show that TRS breaking in Re is due to a form of mixed 
singlet-triplet pairing that has an atomic-scale magnetic texture. Rather 
than assuming an unconventional pairing interaction from the outset, we 
couple a conventional pairing model with an ab initio description of the 
system's magnetism and relativistic electronic structure. We find that a 
triplet pairing component emerges spontaneously due to spin-orbit coupling, 
without further symmetry breaking. When an additional pairing term operating 
in this channel is added in order to make our theory self-consistent a phase 
with broken time-reversal symmetry emerges. Through computer experiments we 
identify the non-symmorphic crystal structure as the key ingredient of this 
exotic new state. Our approach represents a significant departure from 
previous attempts at understanding symmetry-breaking in unconventional 
superconductors, yet it describes experimental data quantitatively with only 
two adjustable parameters, showing that unconventional superconductivity can 
be more ubiquitous than hitherto assumed.Tuesday, 28 September 2021, 10:00
Bldg.1, auditorium, 
https://teams.microsoft.com/l/meetup-join/19%3ace423c05cd1543ab9f9905886590ad69%40thread.tacv2/1632392237061?context=%7b%22Tid%22%3a%224d7ddeef-14ff-4911-8c11-401c69384d77%22%2c%22Oid%22%3a%22969d2d4a-5ba8-43f1-bd69-93f0998b025f%22%7d
Language of the talk: English
All interested are welcome!
Róbert Juhászszfi-seminar AT wigner.mta.hu

The seminar is a hybrid event. The number of participants present in the 
meeting room is limited to 20. Wearing a mask is mandatory.