Microwave spectroscopy on heavy-fermion systems: probing the dynamics of charges and magnetic moments

Abstract

Investigating solids with light gives direct access to charge dynamics, electronic and magnetic excitations. For heavy fermions, one has to adjust the frequency of the probing light to the small characteristic energy scales, leading to spectroscopy with microwaves. We review general concepts of the frequency-dependent conductivity of heavy fermions, including the slow Drude relaxation and the transition to a superconducting state, which we also demonstrate with experimental data taken on UPd2Al3. We discuss the optical response of a Fermi liquid and how it might be observed in heavy fermions. Microwave studies with focus on quantum criticality in heavy fermions concern the charge response, but also the magnetic moments can be addressed via electron spin resonance (ESR). We discuss the case of YbRh2Si2, the open questions concerning ESR of heavy fermions, and how these might be addressed in the future. This includes an overview of the presently available experimental techniques for microwave studies on heavy fermions, with a focus on broadband studies using the Corbino approach and on planar superconducting resonators.

arXiv comment11 pages, 6 figures, proceedings of QCnP 2012

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Cited by in corpus (30)

• Gapped magnetic ground state in quantum-spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$-Cu${}_2$(CN)${}_3$
• Optical response of correlated electron systems
• Single-gap superconductivity and dome of superfluid density in Nb-doped SrTiO3
• Observing electron spin resonance between 0.1 and 67 GHz at temperatures between 50 mK and 300 K using broadband metallic coplanar waveguides
• Low-energy electronic properties of clean CaRuO${}_3$: elusive Landau quasiparticles
• Surface-resistance measurements using superconducting stripline resonators
• Superconducting Energy Scales and Anomalous Dissipative Conductivity in Thin Films of Molybdenum Nitride
• Metallic coplanar resonators optimized for low-temperature measurements
• Improving superconducting resonators in magnetic fields by reduced field-focussing and engineered flux screening
• Superconducting coplanar microwave resonators with operating frequencies up to 50 GHz
• THz conductivity of Sr${}_{1-x}$Ca${}_x$RuO${}_3$
• Microwave study of superconducting Sn films above and below percolation
• Complete electrodynamics of a BCS superconductor with $\mu$eV energy scales: microwave spectroscopy on titanium at mK temperatures
• Superconducting Pb stripline resonators in parallel magnetic field and their application for microwave spectroscopy
• Terahertz Conductivity of the Heavy-Fermion State in CeCoIn5
• Cryogenic frequency-domain electron spin resonance spectrometer based on coplanar waveguides and field modulation
• Characterizing dielectric properties of ultra-thin films using superconducting coplanar microwave resonators
• Is the optical conductivity of heavy fermion strange metals Planckian?
• Optimization of Coplanar Waveguide Resonators for ESR Studies on Metals
• Niobium stripline resonators for microwave studies on superconductors
• Electronic properties of air-sensitive nanomaterials probed with microwave impedance measurements
• Development of planar microstrip resonators for electron spin resonance spectroscopy
• Role of non-linear effects and standing waves in microwave spectroscopy: Corbino measurements on superconductors and VO${}_2$
• Microwave probing of bulk dielectrics using superconducting coplanar resonators in distant-flip-chip geometry
• Characterization of harmonic modes and parasitic resonances in multi-mode superconducting coplanar resonators
• Angle-dependent electron spin resonance of YbRh${}_2$Si${}_2$ measured with planar microwave resonators and in-situ rotation
• Charge Carrier Dynamics of the Heavy Fermion Metal CeCoIn${}_5$ Probed by THz Spectroscopy
• Anomalous Microwave Surface Resistance of CeCu6
• Superconducting microwave oscillators as detectors for ESR spectroscopy
• Gapped magnetic ground state in the spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$Ag${}_2$(CN)${}_3$ suggested by magnetic spectroscopy