Magnetotransport properties of a single-atom-thick GdPb3 kagome compound on Si(111)

Abstract

Synthesis of low-dimensional magnetic materials and control of their properties are demanding tasks for nanotechnology and materials research. We report on the resistance and magnetoresistance measurements of the single-atomic-layer GdPb₃, LaPb₃, YbPb₃ and Gd_xYb_1−xPb₃-periodic kagome compounds on Si(111); the measurements were conducted in situ using the four-point-probe technique in the temperature range from 2.5 to 33 K and magnetic fields from −8 to +8 T. Most attention was paid to the GdPb₃ samples; their transport and magnetotransport measurements revealed occurrence of two critical temperatures, 6 and 25 K. At temperatures below 25 K, which can be interpreted as a Curie temperature, the GdPb₃/Si(111) system exhibits coercivity, associated typically with ferromagnetic-like ordering. Density-functional-theory calculations demonstrated that simple ferromagnetic ordering of Gd atoms is improbable and the magnetic structure of the GdPb₃ layer should be sought among the more complicated ones, and the scale low limit was estimated to be about 2 nm. At a temperature of 6 K, a number of characteristic anomalies are observed in the transport and magnetotransport properties, related possibly to the antiferromagnetic ordering. However the sole magnetoresistance data yield only hints and prospective investigations with other techniques (e.g., spin-polarized scanning tunneling microscopy and Hall measurements) are highly desirable for the further exploration of this unique system exhibiting low-dimensional magnetism at the atomic-scale limit of the film thickness.