Ab Initio Study on Tuning the Ferroelectricity of Orthorhombic HfO2

The origin of the ferroelectricity in HfO
2
is considered to be the formation of the non-centrosymmetric polar orthorhombic phase. The double-well energy landscape as a function of the polarization for orthorhombic HfO
2
is obtained using density functional computations. Our calculation shows that the orthorhombic HfO
2
has the remnant polarization of $66.25 \mu \mathrm{C}$ cm $^{-2}$ and a barrier height of 77.4 meV atom $^{-1}$ for polarization switching. Two methods (doping with Zr and applying biaxial strain) are theoretically investigated to adjust the ferroelectricity of the orthorhombic HfO
2
. Moreover, both single- and double-domain HfO
2
structures are calculated and discussed in this work. We found the ferroelectricity of HfO
2
could be stabilized under tensile strain.