Short-range antiferromagnetic interaction and spin-phonon coupling in La2CoMnO6 double perovskite

TL;DR

This study uses Raman spectroscopy to reveal short-range antiferromagnetic interactions and spin-phonon coupling in La2CoMnO6, highlighting the technique's sensitivity to magnetic disorder and lattice changes beyond bulk magnetic measurements.

Contribution

It demonstrates Raman spectroscopy's effectiveness in detecting short-range magnetic interactions and antisite disorder in double perovskites, which are not observable through traditional magnetic measurements.

Findings

Detection of short-range AF interaction at Tc~135 K

Identification of additional spin-phonon coupling

Raman spectroscopy as a tool for magnetic disorder analysis

Abstract

Weak antiferromagnetic (AF) interaction in the ferromagnetic (FM) partially ordered La2CoMnO6 (LCMO) was detected by Raman spectroscopy by monitoring spin-phonon coupling. Because of the sensibility to probe short-range disorder and lattice modifications, the Raman spectroscopy showed to be an useful tool to indicate less remarkable magnetic transitions in LCMO compound. Apart from the expected spin-phonon coupling due to the long-range FM superexchange (Tc~230 K), phonons parameters pointed out an additional spin-phonon coupling related to the short-range AF interaction at Tc~135 K, which was not detected from the magnetic bulk response. These results reinforce the Raman spectroscopy as a powerful technique to detect antisite disorder into A2B'B"O6 magnetic double perovskites, whose magnetic properties are driven by superexchange interactions.