Strange Metal State Near a Heavy-Fermion Quantum Critical Point
Yung-Yeh Chang1*, Silke Paschen3,4, Chung-Hou Chung1,4
1Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
3Physics and Astronomy Department, Rice University, Houston, Texas, 77251, USA
4Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan
* presenting author:Yung-Yeh Chang,
Recent experiments on quantum criticality in the Ge-substituted heavy-electron material YbRh2Si2 (YRS) under magnetic fields have revealed a non-Fermi-Liquid (NFL) ”strange metal (SM)” state over a finite range of fields at low temperatures, which still remains a puzzle. In the SM state, the zero-field antiferromagnetism is suppressed and the material is in proximity to a heavy Fermi-liquid with Kondo correlation. Above a critical field, the SM phase gives way to the T (temperature)-linear resistivity and the T-logarithmic followed by a power-law singularity in the specific heat coefficient at low T, salient NFL behaviours in the SM region, are un-explained. We offer a mechanism to address these open issues theoreti- cally based on the competition between a quasi-2d fluctuating short-ranged resonant-valence-bonds (RVB) spin-liquid and the Kondo correlation. Via a field-theoretical renormalization group analysis on an effective field theory beyond a large-N approach to an anti-ferromagnetic Kondo-Heisenberg model, we identify the critical point, and explain remarkably well both the crossovers and the SM behaviour.

Keywords: Quantum Criticality, Non-Fermi Liquid Behavior, Strange metal, Renormalization Group