Topological phases combining superconductivity and magnetism.
Relazione su invito
II - Fisica della materia
GSSI Ex ISEF - Aula C - Mercoledì 25 h 16:30 - 19:00
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The search for new variants of semimetals (SMs) recently highlighted the interplay of Dirac fermions physics and magnetism. Indeed, while most of the currently known SMs are non-magnetic, antiferromagnetic (AFM) SMs can be obtained where both time and inversion are broken while their combination is kept or due to chiral- and time-symmetry combined with non-symmorphic transformations. We discuss specific platforms of non-symmorphic antiferromagnets with glide reflection symmetry and demonstrate the path to topological nodal states. Apart from the large variety of fundamental aspects related to Dirac systems, the combination with other types of conventional orders $(e.g.$ magnetism or superconductivity) represents an ideal testbed for achieving new phases of matter and single out materials for future technologies. We will consider the impact of $s$-wave spin-singlet pairing on AFM-SMs with Dirac points or nodal loops at the Fermi level. The electron pairing is generally shown to convert the semimetal into a tuneable nodal superconductor. The changeover from fully gapped to gapless phases is dictated by symmetry properties of the AFM-superconducting state that set the occurrence of a large variety of electronic topological transitions. We provide a general criterion for predicting a series of transitions between nodal and fully gapped superconducting phases. Finally, I will present basic examples of quantum platforms marked by spin-singlet or triplet pairing interfaced with non-trivial magnetic patterns and discuss the nature and the consequences of the emerging topological superconductors.