Tuning the Magnetization of Manganese (II) Carbonate by Intracrystalline Amino Acids

TL;DR

This study demonstrates that incorporating specific amino acids into manganese (II) carbonate crystals can significantly modify their magnetic properties, with effects varying between room temperature and below the Néel temperature, revealing new ways to tune magnetic behavior.

Contribution

The paper introduces a novel method of tuning magnetic properties of MnCO3 by intracrystalline amino acid incorporation, inspired by biomineralization processes.

Findings

Amino acid incorporation decreases magnetic susceptibility at room temperature.

Below the Néel temperature, magnetic susceptibility increases with amino acid incorporation.

Amino acids alter the Néel phase transition temperature and orbital interactions.

Abstract

Incorporation of organic molecules into the lattice of inorganic crystalline hosts is a common phenomenon in biomineralization, and has been shown to alter various properties of the crystalline host. Taking this phenomenon as our source of inspiration, we show herein that incorporation of specific single amino acids into the lattice of manganese (II) carbonate strongly alters its inherent magnetic properties. At room temperature, the magnetic susceptibility of the amino-acid-incorporating paramagnetic MnCO3 decreases, following a simple rule of mixtures. When cooled below the N\'eel temperature, however, the opposite trend is observed, namely an increase in magnetic susceptibility measured in a high magnetic field. Such an increase, accompanied by a drastic change in the N'eel phase transformation temperature, results from a decrease in MnCO3 orbital overlapping and the weakening of superexchange interactions.