Quantum spin liquids (QSLs) are unconventional states of matter characterized by strong quantum correlations and entanglement, in which magnetic moments remain disordered down to the lowest temperatures. They may host exotic excitations such as fractional spinons, emergent photons or Majorana fermions, challenging our understanding of quantum matter. Frustrated magnets, including rare-earth pyrochlores, kagome systems and Kitaev materials, provide promising platforms for exploring these states. Their experimental identification and the characterization of their magnetic excitations remain major challenges. This internship aims to investigate candidate quantum spin-liquid materials using complementary experimental techniques, combining high-resolution spectroscopies (NMR, muon spin relaxation and inelastic neutron scattering) with low-temperature thermodynamic measurements (ultrasound and specific heat). These approaches will probe magnetic correlations and low-energy excitations. The student will join the Spectroscopy of Quantum Materials group at the Laboratoire de Physique des Solides (Université Paris-Saclay), benefiting from established international collaborations and expertise in quantum magnetism. The internship offers hands-on experience in advanced experimental techniques and data analysis. A continuation towards a PhD is possible.