Variation of carrier density in semimetals via short-range correlation: A case study with nickelate NdNiO$_2$

TL;DR

This paper demonstrates that short-range magnetic correlations in correlated semimetals can reversely modulate carrier density, revealing a new mechanism influencing material properties and potential functionalities.

Contribution

It introduces a simulation scheme incorporating noncollinear magnetic correlations without long-range order to explain carrier density variations in semimetals.

Findings

Carrier density varies with short-range magnetic correlations.

The mechanism is demonstrated in nickelate NdNiO$_2$.

Short-range correlations influence low-energy electronic properties.

Abstract

Carrier density is one of the key controlling factors of material properties, particularly in controlling the essential correlations in strongly correlated materials. Typically, carrier density is externally tuned by doping or gating and remains fixed below room temperature. Strangely, the carrier density in correlated semimetals is often found to vary sensitively against weak external controls such as temperature, magnetic field, and pressure. Here, we develop a realistic simulation scheme that incorporates interatomic noncollinear magnetic correlation without a long-range order. Using the recently discovered nickelate superconductor as an example, we demonstrate a rather generic low-energy mechanism that in semimetals short-range correlation can reversely modulate the carrier density as well. Such a mutual influence between correlation and carrier density provides an extra ingredient for sensitive bifurcating behavior. This special feature of correlated semimetals explains their versatile carrier density at low energy and opens up new possibilities of functionalizing these materials.