Potential barrier formed at domain boundaries in twinned tetragonal BaTiO_3 single crystals

摘要

An n-type barium titanate (BaTiO_3) single crystal with domain structures has been investigated using electronic transport and X-ray photoemission measurements. Although cubic BaTiO_3 showed transport behavior with only small departures from isotropy above its Curie temperature (T_c), twinned tetragonal BaTiO_3 showed high anisotropy in electrical resistance. Indeed, the resistance in twinned BaTiO_3 was high for the current flowing across the domain boundaries (DBs) and low for that parallel to the DBs. A photoemission study performed under an external bias indicated that a potential drop occurs at every DB. These results indicate that DBs in tetragonal BaTiO_3 act as resistances causing anisotropic transport in twinned BaTiO_3.