Effective Mass for Holes in Paramagnetic, Plasmonic Cu₅FeS₄ Semiconductor Nanocrystals

The impact of a magneto-structural phase transition on the carrier effective mass in Cu₅FeS₄ plasmonic semiconductor nanocrystals was examined using Magnetic Circular Dichroism (MCD). Through MCD, the sample was confirmed as p-type from variable temperature studies from 1.8 - 75 K. Magnetic field dependent behavior is observed, showing an asymptotic behavior at high field with an $$ value 5.98 $$ at 10 T and 2.73 $$ at 2 T. Experimentally obtained results are holistically compared to SQUID magnetization data and DFT results, highlighting a dependency on vacancy driven polaronic coupling, magnetocrystalline anisotropy, and plasmon coupling of the magnetic field all contributing to an overall decrease in the hole mean free path dependent on the magnetic field applied to Cu₅FeS₄.