ESR of MnO embedded in silica nanoporous matrices with different topologies

TL;DR

This study investigates how the topology of silica nanoporous matrices influences the electron spin resonance signals of confined MnO, revealing differences in crystalline and amorphous phases depending on pore size and structure.

Contribution

It provides new insights into the ESR behavior of MnO confined in different nanoporous topologies, highlighting the effects of pore size and structure on magnetic properties.

Findings

Crystallized MnO behavior resembles bulk in porous glass.

Disordered surface spins produce strong ESR signals below transition.

Smaller channels increase amorphous MnO fraction.

Abstract

Electron spin resonance (ESR) experiments were performed with antiferromagnetic MnO confined within a porous vycor-type glass and within MCM-type channel matrices. A signal from confined MnO shows two components from crystallized and amorphous MnO and depends on the pore topology. Crystallized MnO within a porous glass shows a behavior having many similarities to the bulk. In contrast with the bulk the strong ESR signal due to disordered "surface" spins is observed below the magnetic transition. With the decrease of channel diameter the fraction of amorphous MnO increases while the amount of crystallized MnO decreases. The mutual influence of amorphous and crystalline MnO is observed in the matrices with a larger channel diameter. In the matrices with a smaller channel diameter the ESR signal mainly originates from amorphous MnO and its behavior is typical for the highly disordered magnetic system.