Temperature-driven massless fermions in HgCdTe heterostructures

HgCdTe compounds can be engineered to fabricate “gapped-at-will” structures. Therefore, 1D, 2D and even 3D massless particles can be observed in topological phase transitions driven by intrinsic and external physical parameters. In this work, we report on our experimental results, obtained by temperature-dependent Terahertz and Mid-Infrared magneto-spectroscopy, of topological phase transitions in HgCdTe-based quantum wells and bulk samples. These transitions are accompanied with the appearance of 2D and 3D massless particles called Dirac and Kane fermions, respectively.