Ferromagnetic instability of interlayer floating electrons in quasi-two-dimensional electride Y$_2$C

TL;DR

This study reveals that the quasi-two-dimensional electride Y$_2$C exhibits ferromagnetic tendencies due to interlayer electrons, with its band structure's semimetallic and two-dimensional nature being crucial for this magnetic behavior.

Contribution

The paper demonstrates through ab initio calculations that Y$_2$C's interlayer electrons induce ferromagnetism, highlighting the role of its unique electronic structure.

Findings

Y$_2$C$ is a weak itinerant ferromagnet or near ferromagnetic instability.

Electrons in Y$_2$C form two-dimensional interlayer conduction bands.

Semimetallicity and two-dimensionality are key to ferromagnetic behavior.

Abstract

Ab initio electronic structure calculations show that the recently identified quasi-two-dimensional electride Y$_2$C is a weak itinerant ferromagnet or at least close to a ferromagnetic instability. The ferromagnetism is induced by the electride electrons, which are loosely bound around interstitial sites and overlap with each other to form two-dimensional interlayer conduction bands. The semimetallicity and two-dimensionality of the band structure are the key to understanding this ferromagnetic instability.