High Magnetic Field Behavior of Novel Phases in YbB₁₂

Large magnetic fields have dramatic effects on electron motion. In (semi)metallic systems, these effects are particularly pronounced because electron states are quantized into Landau levels causing oscillatory behavior in physical observables, known as quantum oscillations (QOs). QOs are important probes of electronic structure, but historically have been limited to (semi)metallic systems. As such, QOs in the magnetization and resistivity of YbB₁₂ are surprising because YbB₁₂ is nominally an insulator with small hybridization gaps at low temperatures. These observations in YbB₁₂, and similar systems, are exciting owing to implications for topologically-protected surface states or a bulk neutral Fermi surface, but their origin is still not understood. In addition to these unconventional QOs, YbB₁₂ hosts a strongly-correlated metallic state accessible by high fields. The possibility of a connection between the insulating ground state and field-induced metallic state remains unclear.

Using a combination of conventional transport, contactless transport, and magnetometry in pulsed magnets, we study the angular and temperature dependence of quantum oscillations in both the insulating and metallic states of YbB₁₂. Our results demonstrate that quantum oscillations in YbB₁₂ are robust and reproducible. Additionally, we examine the angular and temperature dependence of the insulator-metal transition. Together, these measurements help clarify the high field behavior of novel phases in YbB₁₂.