Thickness evolution of transport properties in exfoliated Fe1+y Te nanoflakes

We report the evolution of transport properties in exfoliated Fe_1+y Te (y  =  0.04) nanoflakes of various thickness. In contrast to the sharp semiconducting-to-metallic phase transition observed in both bulk and thicker flakes, this transition becomes broadened for flakes with an intermediate thickness followed by the appearance of a superconducting-like feature upon further cooling. With the thickness further decreased, the flakes exhibit insulating transport behavior with significantly enhanced positive magnetoresistance, which can be explained using a variable range hopping mechanism, suggesting the nature of a highly disordered 2D system.