Dimensional crossover in layered $f$-electron superlattices

TL;DR

This paper investigates how heavy electrons form and behave in layered f-electron superlattices, revealing a temperature-dependent crossover from two- to three-dimensional electronic states that impacts magnetic and superconducting properties.

Contribution

It demonstrates the existence of two distinct coherence temperatures and a dimensional crossover in heavy electron systems using dynamical mean field theory.

Findings

Heavy electrons form below temperature T0 across the system.

Two coherence temperatures T_x and T_z are identified for in-plane and out-of-plane resistivities.

A dimensional crossover from 2D to 3D occurs as temperature or layer structure varies.

Abstract

Motivated by the remarkable experimental realizations of $f$-electron superlattices, e.g. CeIn$_3$/LaIn$_3$- and CeCoIn$_5$/YbCoIn$_5$- superlattices, we analyze the formation of heavy electrons in layered $f$-electron superlattices by means of the dynamical mean field theory. We show that the spectral function exhibits formation of heavy electrons in the entire system below a temperature scale $T_0$. However, in terms of transport, two different coherence temperatures $T_x$ and $T_z$ are identified in the in-plane- and the out-of-plane-resistivity, respectively. Remarkably, we find $T_z < T_x \sim T_0$ due to scatterings between different reduced Brillouin zones. The existence of these two distinct energy scales implies a crossover in the dimensionality of the heavy electrons between two and three dimensions as temperature or layer geometry is tuned. This dimensional crossover would be responsible for the characteristic behaviors in the magnetic and superconducting properties observed in the experiments.