Evidence of spin lattice coupling in MnTiO₃: An x-ray diffraction study

¹ School of Basic Sciences, Indian Institute of Technology Mandi - Kamand, Himachal Pradesh-175005, India
² School of Engineering, Indian Institute of Technology Mandi - Kamand, Himachal Pradesh-175005, India

^(a) bindu@iitmandi.ac.in (corresponding author)

Received: 10 February 2015
Accepted: 13 April 2015

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 lattice parameters, which can be divided into three regions. In region I (300 K to 200 K), the lattice parameters show linear temperature dependence due to the thermal effect. In the region II (200 K to 95 K), lattice parameters show deviation from the linear behaviour due the competing intra-layer antiferromagnetic interactions setting in . The c/a ratio is 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 . In region III (95 K to 23 K), the lattice parameter c shows negative thermal expansion where 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.