Quantum Monte Carlo finds two paths for heavy electron transport

Gaopei Pan and Fakher F. Assaad of Universität Würzburg used sign-problem-free determinant quantum Monte Carlo simulations to reveal two distinct pathways for heavy electron transport within a U(1) lattice gauge model. Their work identifies a heavy-fermion metal characterized by robust low-frequency transport alongside a Kondo-breakdown metal exhibiting vanishing transport at low frequencies, demonstrating that heavy electron behavior is not a single, predictable phenomenon. The researchers found that the Luttinger volume, a measure of electron count, differs significantly between these regimes, counting both composite and conduction electrons in the heavy-fermion phase but only conduction electrons in the Kondo-breakdown phase. This evolution, detailed through analysis of composite-fermion spectra and optical conductivity, provides a nonperturbative demonstration of gauge-mediated Kondo breakdown. Gaopei Pan of Universität Würzburg and Fakher F. Assaad detailed a U(1) lattice gauge model revealing two distinct regimes governing heavy electron…