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DESCRIPTION:Professor Yi Li \, Johns Hopkins University\n\n
Althoug
h the existence of magnetic \;monopoles \;is admitted by\;
\;the fund
amental laws\, the real \;monopoles \;in nature remain elusive.\;
R
03\;N
evertheless\, variations of \;monopoles \;appear in realistic cond
ensed
\; \;matter systems\, from quantum Hall effects\; to \;\;topological\; \
;supe
rconductivity\;\, which spur a race to discover new exotic\; \;topological phases
of matter. In this talk\, we will present a\; \;dramatic effect \;\;arising
from topological\; Fermi surface\;
s -- \;a novel topological class of supercon
ductivity and density-wave orders\;: \;\;When \;the ordered pairs acquire
span>\; \;
span>non-tri
vial two-particle Berry phases\, their pairing phases cannot be\;<
/span> \;global
ly well-defined in the momentum space. Therefore\, the\; \;conventional de
scription of superconducting pairing symmetries in\; \;terms of spherical
harmonics (e.g. s-\, p-\, d-waves) ceases to apply.\; \
;Instead\, they a
re characterized by \;topologically protected nodal gap functions 
\;rep
resented by \;monopole \;harmonic functions. This so-called &ldquo
\;monopole harmonic order&rdquo\; is expected to be realized and detected
in Weyl semimetal materials.
\n
DTSTART:20191205T160000Z
LOCATION:Physics Building\, Room 313
SUMMARY:Monopole Superconductivity and Density-Wave Order in Weyl Semi-meta
ls
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