  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.
