TiO2 has, in recent years, become a hot subject as it holds a promise for spintronic application. Recent experimental study on anatase Ti1-xTa x O2 (x ∼ 0.05) thin films shows that the system changes from non-magnetic to ferromagnetic due to Ti vacancies that are formed when a small percentage of Ti atoms are substituted by Ta. Motivated by those results that reveal the ferromagnetic phase at room temperature, we conduct a theoretical study on the temperature-dependent magnetization and the Currie temperature of that system. We hypothesize that when several Ti vacancies are formed in the system, each of them induces a local magnetic moment, then such moments couple each other through Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, forming a ferromagnetic order. To study the temperature dependence of the magnetization and predict the Curie temperature, we construct a tight-binding based Hamiltonian for this system and use the method of dynamical mean-field theory to perform calculations for various temperatures. Our work is still preliminary. The model and method may need further improvement to be consistent with known existing facts. We present our preliminary results to show how the present model works.
|Journal||IOP Conference Series: Materials Science and Engineering|
|Publication status||Published - 2 May 2017|
|Event||International Symposium on Current Progress in Functional Materials 2016, ISCPFM 2016 - Bali, Indonesia|
Duration: 26 Jul 2016 → 27 Jul 2016