Interplay of Spin, Lattice, and Charge Degrees of Freedom in Ca3Mn2O7

TL;DR

This study uses synchrotron X-ray diffraction to explore how spin, lattice, and charge interactions influence structural and magnetic properties in Ca3Mn2O7, revealing strong spin-lattice coupling and magneto-dielectric effects.

Contribution

It provides detailed experimental evidence of spin-lattice-charge interplay and establishes the presence of intrinsic magneto-dielectricity in Ca3Mn2O7.

Findings

Identification of spin-ordering signatures via bond angle changes

Observation of temperature anomalies in volume and polarization

Confirmation of magneto-dielectric coupling under magnetic field

Abstract

From low-temperature Synchrotron X-ray diffraction, a precise thermal characterization of octahedral distortions in single phase Ruddlesden-Popper Ca3Mn2O7 is performed. Highly sensitive close-steps temperature dependences of Mn-O-Mn bond angles connecting MnO6 octahedra clearly reveal signature of the spin-ordering in the system. Spin-lattice coupling is thus established via the structural distortions responsible for evolution of the magnetic state. Further, temperature anomalies observed here in volume and polarization-measure of the unit cell highlight the interplay between spin, lattice and charge degrees of freedom. Dipole-relaxation characteristics examined under applied magnetic field consistently corroborate the concurrent magnetic and structural changes, in terms of genuine and intrinsic magneto-dielectricity.