Quasiparticle scattering spectroscopy (QPS) of Kondo lattice heavy fermions

Point-contact spectroscopy (PCS) is a powerful technique to study electronic properties via measurements of non-linear current-voltage characteristic across a ballistic junction. It has been frequently adopted to investigate novel and/or unconventional superconductors by detecting the energy-dependent Andreev scattering. PCS of non-superconducting materials has been much rarely reported. From our recent studies on heavy fermions [1], we have frequently observed strongly bias-dependent and asymmetric conductance behaviors. Based on a Fano resonance model in a Kondo lattice [2], we attribute them to energy-dependent quasiparticle scattering off hybridized renormalized electronic states, dubbing it QPS. We will present our QPS results on several heavy-fermion systems and discuss QPS as a novel technique to probe the bulk spectroscopic properties of the electronic structure. For instance, it reveals that the hybridization gap in URu$_{2}$Si$_{2}$ opens well above the hidden order transition [1].\\[4pt] [1] W. K. Park \textit{et al}., PRL \textbf{108}, 246403 (2012); \textit{ibid.,} \textbf{100}, 177001 (2008).\\[0pt] [2] M. Maltseva, M. Dzero, P. Coleman, PRL \textbf{103}, 206402 (2009).