Metal-insulator transition in La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ (x=0.59) revealed by ARPES

Using angle-resolved photoemission spectroscopy (ARPES), we studied the metal-insulator transition of La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ (x=0.59). Below T$_{C}$, there is significant metallic weight at the Fermi level, while a gap opens above T$_{C}$, in excellent agreement with resistivity measurements. We also found that in this compound the metal-insulator transition is associated with a remarkable coherent-incoherent weight transfer from the dispersive band to a non-dispersive feature over a large energy scale. The band dispersion also shows an unusual change with increasing temperature, suggesting complicated interactions in this material.