TDO as AMRO; Finding g* in Organic Superconductors with an Untraditional Tunnel Diode Oscillator Technique

The renormalized gyromagnetic ratio, g*, which accounts for many-body effects and is also related to Wilson’s ratio, is an important, yet underreported quantity in low-dimensional superconductivity that links magnetic susceptibility to the Sommerfeld coefficient, γ, in electronic specific heat data. In crystals with quantum oscillation orbits from multiple parts of the Fermi surface, amplitude ratios of Shubnikov-de Haas (SdH) oscillations can be fit to the Lifshitz-Kosevich formula to find g*, but this cannot be done in crystals with only one orbit. Alternatively, spin-zeroes, angles where SdH oscillation amplitudes vanish, also define g* and can be found using traditional (tedious) B-Field sweeps or by AMRO techniques. Using a contactless tunnel diode oscillator (TDO) measurement technique, we report g* in multiple Q2D organic superconductors not only from traditional field-dependent data, but we also reproduce previous AMRO data in κ-(ET)₂Cu(NCS)₂. In the future, we hope to study angular-dependent parameters of Q2D organic superconductors with the TDO as a new, unconventional AMRO-style device.