ELFT HÍRADÓ

[Szeminárium koordinátor <sem-admin AT szfki.hu>]

SZFI SeminarCsire GáborBarcelona Institute of Science and 
TechnologyUnconventional magnetically-textured superconductivity in elemental 
rhenium crystalsTuesday, 2 November 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%7dWhen
 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. Minden érdeklődőt szívesen 
látunk! - Everyone is welcome to attend.Róbert Juhászsem-admin AT szfki.hu