Dielectric properties of relaxor CuCrO2 at room temperature

Abstract

The dielectric properties of CuCrO2 bulk and thin films are studied by evaluating the complex dielectric function ε. In addition to the small peak near the Néel temperature 𝑇N, a secondary broad peak is found at high temperatures around 𝑇m=450 K≫𝑇N. As a feature of relaxor ferroelectrics, the maximum temperature 𝑇m increases with increasing frequency. The real part of ε decreases with increasing magnetic field h and the peak at 𝑇N vanishes. The secondary peak becomes smaller and is broadened with increasing magnetic field. ε increases with increasing film thickness. Near 𝑇m, the dielectric function offers a critical behavior expressed by an exponent 𝛾=1.74. Using scaling arguments, critical exponents 𝛽=0.13 and 𝛿=13.38 are deduced. The exponents depend on the film thickness. While β increases, the exponent γ is reduced with increasing film thickness.