Evidence of spin lattice coupling in MnTiO ₃ : An x-ray diffraction study

Abstract

Here we investigate the temperature evolution of the structural parameters of a potential magnetoelectric material, MnTiO3. The experimental results reveal interesting temperature dependence of the c/a ratio and the Mn-O bonds which can be divided into three regions. In region I (300 K to 200 K), the above parameters are seen to decrease with decrease in temperature due to thermal effect. In the region II (200 K to 95 K), the decrement in the structural parameters are reduced due the competing intra layer antiferromagnetic interaction setting in ∼ 200 K. The c/a ratio are seen to display a minima around 140 K. Below 140 K, the short Mn-O bonds increase suggesting the onset of inter layer antiferromagnetic interaction ∼ 100 K. In region III (95 K to 23 K), the antiferromagnetic interaction is fully established. The behaviour of the calculated Mn-O bonds based on first principle calculations are in line with the experimental results. This study demonstrates the importance of spin lattice coupling in understanding the magnetic properties of the compound which is expected to be helpful in revealing the origin of magnetically induced ferroelectricity.

Structural response to the magnetic pre-ordering in LiFeSi2O6

“…In the case of Ca 3 Co 2 O 6 compound, Mossbauer studies have also shown similar behaviour 16 . Similarly, in the case of quasi two dimensonal MnTiO 3 compound, our structural studies have shown clear signature of the onset of the magnetism within the ab-plane stabilizing at higher temperature than the onset of the magnetism between the planes 17 .…”

Structural evolution of MnTi0·8Ru0·2O3

“…So, here the lattice parameter a is showing a very less deviation from the linear thermal behaviour up to the lowest temperature 26K. But for x=0 compound the situation is different 12 .…”

“…In the recent study done by H. J. Silverstein et al it has been proposed that the local spin lattice coupling is not weak and it is much more important for the magnetoelectric properties of this compound 13 . In our previous study 12 , the Mn-O, Mn-Mn and Ti-O bonds are showing significant changes across the region of intraand inter-layer antiferromagnetic interactions. The changes in Mn-O and Mn-Mn bonds across the onset temperature for 2D and 3D AFM is understandable but the changes in the Ti-O bonds at these temperature regions is not understandable .…”

“…The non-appearance of dielectric anomaly due to spin lattice coupling indicates that the nature of the spin structure is such that no break in spatial symmetry observed. But in our recent study we found that in MnTiO 3 the spin lattice coupling is not weak in the absence of external magnetic field 12 . Hence the nonappearance of dielectric anomaly in MnTiO 3 does not mean that the spin lattice coupling is weak.…”

Nano-mechanical behavior of MnTiO3 ceramics

“…Within the layer (intra-layer), two Mn spins interact to each other through O ion via superexchange interaction and between the layer (inter-layer) through two O ions via super-superexchange interaction 11 . The intra-layer interactions are stronger than the inter-layer interactions.…”