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MEM-C IRG-2: Nematic Fluctuations in an Orbital Selective Superconductor Fe1+yTe1-xSex

Electronic  nematicity  is  a  correlated  electronic  state  in  solids  that spontaneously breaks rotational symmetry. This work found that in Fe1+yTe1-xSex,  one  of  the  most  strongly  correlated  iron-based superconductors,   electronic   nematicity   is   closely   linked   to magnetism,   and   its   fluctuations   may   be   responsible   for superconducting pairing.

Although  the  relationship  between  nematicity,  magnetism,  and superconductivity   has   been   observed   in   some   iron-based superconductor families, it remained unclear whether this correlation would persist when the system is pushed to the strongly correlated limit.  This  limit  involves  a  metal-insulator  transition  in  part  of  the energy  spectrum  known  as  the  orbital  selective  Mott  transition (OSMT),  which  has  been  observed  in  Fe1+yTe1-xSex.  This  study showed  that  nematic  fluctuations  in  Fe1+yTe1-xSex  not  only  closely follow magnetic fluctuations but also exhibit an unusual temperature dependence resulting from the OSMT.

The observation of nematic fluctuations in Fe1+yTe1-xSex underscores its  universal  significance  in  iron-based  superconductors,  thereby paving  the  way  for  the  manipulation  and  utilization  of  phase transitions in layered materials for practical applications.