Fabrication And Characterization Of Heterostructure Of Multiferroic TbMnO₃and TbFeO₃Films

Singal multiferroics are materials in which two or more than two primary ferroic order parameters coexist simultaneously. The multiferroics researched recently are the materials with both ferroelectric order and magnetic order structures. The coexistence of magnetism and ferroelectricity in this kind of materials supplies them magneto-electric effects. Ferroelectromagnets have great potential in the field of information storage, spin electronics, non-linear magnet-light effect and transducer with coexist simultaneously of ferroelectric, ferromagnetic and magneto-electric effects.At present most attention has been focused on the bulk multiferroics, but for multiferroics thin film, there was only few reports, especially for heterostructure constructed by multiferroics and other materials. Therefore, we have done some research about the heterostructure of multiferroic TbMnO3and TbFeO3films.TbMnO3and TbFeO3thin films were fabricated by RF magnetron sputtering method. The structure, ingredient, morphology and electrical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and low temperature electrical transport measurement system, respectively. The major results and conclusions can be summarized as followings:1. Single phase TbMnO3and TbFeO3materials were synthesized by the conventional solid-state reaction method, and then TbMnO3、 TbFeO3targets were prepared for film deposition. RF magnetron sputtering technique was used to deposite TbMnO3thin films on SrTiO3(001), TbFeO3thin films on SrTiO3(100), and TbFeO3thin films on n-type Si (n-Si). The influence of the deposition parameters (such as substrate temperature, pressure, power and target-substrate distance) on crystal structure of film was studied. The optimized process was obtained for depositing high quality oriented TbMnO3and TbFeO3thin films.2. TbMnO3/Nb-SrTiO3heterostructure was prepared on1.0wt%Nb doped SrTiO3(001) substrate and the electrical transport properties were studied. The results show that the conduction mechanism is Schottky-emission-like conduction above175K and space-charge-limited conduction below175K in case of forward bias, a space-charge-limited conduction mechanism for whole temperature range in case of reversed bias. The electrical transport properties of TbMnO3/Nb-SrTiO3heterostructure displayed magnetic-electric coupling effect at～25K, which is related to the change of Mn3+spins order.3. TbFeO3/Nb-SrTiO3heterostructure was prepared on1.0wt%Nb doped SrTiO3(100) substrate and the electrical transport properties were studied. The results show that TbFeO3/Nb-SrTiO3p-n heterostructure performs an obvious rectifying behavior during25-300K temperature range and the ratio of rectification increased with increasing of temperature. The electrical transport properties of TbFeO3/Nb-SrTiO3heterostructure displayed magnetic-electric coupling effect at-120K, which is related to the change of Fe3+spins order. The conduction mechanism is Schottky-emission-like conduction above TN and space-charge-limited below TN vin case of forward bias, a space-charge-limited conduction mechanism for whole temperature range in case of reversed bias. Further more, above175K, the anomalous increasing current with decreasing temperature is due to the tunneling current through TFO/NSTO junction.4. TbFeO3/n-Si heterostructure was prepared on (100) n-Si and the electrical transport properties were studied. The results show that TbFeO3/n-Si heterostructure performs rectifying behavior during5-300K temperature range, especially in250-300K temperature range, the rectifying behavior is obvious.