Anomalous diamagnetism of electride electrons in transition metal silicides

TL;DR

This study reveals that electride electrons in transition metal silicides exhibit anomalous diamagnetism, which diminishes with hydrogen absorption, indicating a unique magnetic property linked to electride behavior and hydrogen interaction.

Contribution

It provides experimental evidence of anomalous diamagnetism in electride electrons within transition metal silicides using muon spin rotation, highlighting their unique magnetic properties.

Findings

Electride electrons show large negative magnetic shifts independent of temperature.

Diamagnetic shift decreases as hydrogen content increases.

Electride electrons are absorbed by hydrogen to form hydride ions.

Abstract

Intermetallic silicide compounds, LaScSi and Y$_5$Si$_3$, known for being hydrogen (H) storage materials, are drawing attention as candidates for electrides in which anions are substituted by unbound electrons. It is inferred from a muon spin rotation experiment that the local field at the muon site (which is the same site as that for H) in these compounds exhibits a large negative shift under an external magnetic field, which is mostly independent of temperature. Such anomalous diamagnetism signals a unique property of electride electrons associated with transition metals. Moreover, the diamagnetic shift decreases with increasing H content, suggesting that the electride electrons existing coherently in the hollow interstitial positions are adsorbed by H to form hydride ions (H$^-$)