Dimensional crossover in Sr$_2$RuO$_4$ within slave-boson mean-field theory

TL;DR

This paper investigates the temperature-driven dimensional crossover in Sr$_2$RuO$_4$ using slave-boson mean-field theory, revealing how weak inter-chain hybridization affects spectral density and c-axis transport, aligning with experimental observations.

Contribution

It introduces a two-orbital Hubbard model analyzed with SBMFT to study correlation effects and the dimensional crossover in Sr$_2$RuO$_4$, providing insights into quasiparticle emergence and transport behavior.

Findings

Identification of a temperature-dependent regime change in c-axis transport.

Qualitative agreement with experimental data on spectral density evolution.

Evidence of quasiparticle formation at low temperatures.

Abstract

Motivated by the anomalous temperature dependence of the c-axis resistivity of Sr$_2$RuO$_4$, the dimensional crossover from a network of perpendicular one-dimensional chains to a two-dimensional system due to a weak hybridization between the perpendicular chains is studied. The corresponding two-orbital Hubbard model is treated within a slave-boson mean-field theory (SBMFT) to take correlation effects into account such as the spin-charge separation on the one-dimensional chains. Using an RPA-like formulation for the Green's function of collective spinon-holon excitations the emergence of quasiparticles at low-temperatures is examined. The results are used to discuss the evolution of the spectral density and the c-axis transport within a tunneling approach. For the latter a regime change between low- and high-temperature regime is found in qualitative accordance with experimental data.