Time-resolved low energy dynamics in heavy-fermion systems

Quantum phase transitions (QPT) describe a change between two ground states of a many-body system, controlled by a nonthermal control parameter [1]. Rare-earth heavy-fermion systems show a QPT between a fully Kondo-screened, paramagnetic Fermi-liquid phase and an antiferromagnetically ordered phase. When excited by a terahertz pulse, the heavy quasiparticles disintegrate and coherently recover on a picosecond timescale, characteristic of the Kondo coherence time or inverse Kondo temperature [2]. In my talk, I will demonstrate how terahertz time-domain spectroscopy can be used to probe theKondo quasiparticle spectral weight at such ultrafast timescales. Further, I will elaborate on how we could distinguish contributions from the heavy Kondo band and from the crystal-electric-field (CEF) split satellite bands [3]. I would show our observations on the critical slowing down of quasiparticles as we approach the quantum critical point [4]. We corroborate our observations by temperature-dependent, high-resolution dynamical mean-field calculations for the multi-orbital Anderson lattice model and discuss its relevance for quantum critical scenarios.

[1] 	H. v. L ̈ohneysenet al., Rev. Mod. Phys.79, 1015 (2007).
[2] 	C. Wetli, S. Palet al., Nat. Phys.14, 1103 (2018).
[3] 	S. Palet al., Phys. Rev. Lett.122, 096401 (2019).
[4] 	S. Palet al., in preparation (2019)