MIT News August 12, 2024
For topological Weyl semimetals, there is a pressing need to fine-tune the Fermi level, a critical aspect of quantum materials, to the Weyl nodes and unlock exotic electronic and optoelectronic effects associated with the divergent Berry curvature. However, the situation for bulk crystals poses significant challenges. A team of researchers in the US (MIT, Brookhaven National Laboratory, industry) demonstrated the meV level ultra-fine-tuning of the Fermi level of bulk topological Weyl semimetal tantalum phosphide. By calculating the desired carrier density and controlling the accelerator profiles, the Fermi level could be experimentally fine-tuned from 5 meV below, to 3.8 meV below, to 3.2 meV above the Weyl nodes. The crystalline structure was largely maintained under irradiation, while electrical transport indicated that Weyl nodes were preserved, and carrier mobility was also largely retained. According to the researchers their work demonstrated the viability of this generic approach to tune the Fermi level in semimetal systems and could serve to achieve property fine-tuning for other bulk quantum materials with ultrahigh precision… read more. Open Access TECHNICAL ARTICLE
Ion implantation using a tandem accelerator on bulk material… Credit: Ella Maru Studio