Increase of Neel temperature of magnetoelectric Cr2O3 thin film by epitaxial lattice matching

Increase in the Neel temperature (T-N) of the 10-nm thick Cr2O3(0001) thin films by the lattice strain was experimentally investigated. T-N was determined based on the zero-offset anomalous Hall measurements for the Pt/Cr2O3/Pt epitaxial trilayer. The lattice strain was altered by the Pt buffer layer thickness and was evaluated by the lattice parameters. T-N was increased from 241.5 to 260.0 K by varying the Pt buffer layer thickness from 0 to 20 nm. For the film without the Pt buffer layer, the apparent critical exponent near T-N increased suggesting the distribution of T-N due to the inhomogeneous strain. The T-N value was weakly correlated with the axial ratio c/a and the lattice volume of the Cr2O3 layer V; T-N increases with decreasing c/a or increasing V. The increase in T-N by the reduction in c/a (or by increasing V) implies that the exchange coupling between the nearest neighbor Cr3+ spins has the significant role in the strain effect. published under an exclusive license by AIP Publishing.

Automated summary

The experimental investigation found that the increase in the lattice strain of the Pt buffer layer thickness led to an increase in the Neel temperature (T-N) of the 10-nm thick Cr2O3(0001) thin films. The T-N value increased from 241.5 to 260.0 K with the variation of the Pt buffer layer thickness. The T-N value was weakly correlated with the axial ratio c/a and the lattice volume of the Cr2O3 layer V, increasing with decreasing c/a or increasing V.