The Electronic and Magnetic Properties of Tetragonal Ultrathin BaTiO3 Nanotube

The unique structural, electronic and magnetic properties of intrinsic defect in tetragonal ultrathin BaTiO 3 nanotube ( u -BTONT) have been investigated by first-principle calculations. The zigzag (9,0) u -BTONTs with two different terminations (TiO 2 and BaO) can be formed by rolling up one monolayer BTO along a certain crystallographic axis, and the BaO-terminated NT is more stable than TiO 2 terminated due to its lower binding energy. The oxygen vacancies on the tube are more stable than cation vacancies, and their magnetic coupling is related not only to the kinds of oxygen vacancies but also to the distance of vacancies. Moreover, both Ba and Ti vacancies also can introduce the ferromagnetism in u -BTONT, which is different from the origin of magnetism in BTO bulk and (001) surface. It is indicated that one-dimensional structure with high surface area can make it easier to form more useful vacancies which prefer ferromagnetism. Our work offers a possible route to fabricate the multiferroic materials.