Research Projects

The characterization of quantum phase transitions (QPTs) in solid state physics has become crucial due to the advent of new quantum materials. Conventional measurements like transport, magnetization, and specific heat measurements have been used to identify QPTs, but little attention has been given to the elastic properties of these materials. The elastic constants are inherently associated with the curvature of ground state free energy, making them an important order parameter for probe quantum phase transitions, especially in structural transitions. During my Post-Doc tenure at IISER Pune, we designed a low temperature resonance ultrasound spectroscopy (RUS) set up to accurately measure elastic constants as a function of T. RUS is conceptually simple, does not require large samples, provides all elastic constants in a single measurement over a moderate frequency range, and can provide accurate results at ultra-low T in the presence of high magnetic and electric fields. Recently, RUS has been found to be an essential tool for characterizing nematic fluctuations in unconventional superconductors, such as iron pnictides, which are predicted to provide the pairing glue for the formation of cooper pairs. However, most studies have focused on strain/stress-induced resistivity measurements or anisotropy in the superconducting gap symmetry to probe the effects of nematic fluctuations on superconductivity in iron pnictide single crystals. This study proposes performing T-dependent RUS measurement on doped BaFe2As2 and FeSe1-xSx single crystals to investigate the effects of nematic fluctuations on elastic properties and search for any softening of the elastic constants at the onset of nematic fluctuations.