Presentation Information
[WBP1-13]Study on the Effect of Sr/Ca Composition Ratio in AE-Cu-O Thin Films Prepared by Combinatorial Pulsed Laser Deposition
*Haruto Uchida1, Kazuya Ogasawara1, Shinkuro Suzuki1, Noriyuki Taoka1, Yosiyuki Seike1, Tatsuo Mori1, Toshinori Ozaki2, Shuhei Funaki3, Yusuke Ichino1 (1. Aichi Inst. of Technol. (Japan), 2. Kwansei Gakuin Univ. (Japan), 3. Shimane Univ. (Japan))
Keywords:
Combinational PLD Method,AE-Cu-O,thin film
Currently, commercially available superconducting wires consisting of REBCO (RE = rare earth elements) are facing resource competition due to their production being concentrated in specific regions and their use in other important products. To solve this problem, this study aimed to fabricate rare-earth-free AE-Cu-O superconductors using thin-film technology. An issue with AE-Cu-O is the easy formation of oxygen vacancies on the CuO2 planes, which are responsible for superconductivity.
In this research, thin films were deposited on LaAlO3 (LAO) substrates using the combinatorial PLD method. This technique uses Sr2CuO3 and Ca2CuO3 targets to continuously vary the Sr and Ca composition ratios based on the position on the substrate. The films were fabricated with a Nd:YAG laser, varying the heater temperature from 650-850°C and oxygen pressure from 10-50 Pa. The samples were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and sheet resistance measurements via a movable four-probe method.
XRD measurements of a film deposited at a heater temperature of 750°C and an oxygen pressure of 20 Pa showed diffraction peaks attributed to AECuO2 (AE112). As the substrate position x increased from 0 mm to 10 mm, the diffraction angle increased, and the c-axis length decreased. This decrease in c-axis length is thought to be due to the replacement of the larger Sr2+ ion with the smaller Ca2+ ion. The sheet resistance also tended to increase as x increased. This indicates that the resistance increases with the addition of Ca to the Sr site in the AE112 crystal structure. These results show that the combinatorial PLD method allows for the continuous acquisition of data with varying composition ratios on a single substrate in a single deposition process. However, the intended AE2CuO3 could not be fabricated because the AE ratio in the thin films was too low.
Future efforts will focus on fabricating thin films by increasing the AE ratio in the targets. The objective is to fabricate AE-Cu-O superconductors by optimizing conditions such as heater temperature and oxygen pressure.
In this research, thin films were deposited on LaAlO3 (LAO) substrates using the combinatorial PLD method. This technique uses Sr2CuO3 and Ca2CuO3 targets to continuously vary the Sr and Ca composition ratios based on the position on the substrate. The films were fabricated with a Nd:YAG laser, varying the heater temperature from 650-850°C and oxygen pressure from 10-50 Pa. The samples were evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and sheet resistance measurements via a movable four-probe method.
XRD measurements of a film deposited at a heater temperature of 750°C and an oxygen pressure of 20 Pa showed diffraction peaks attributed to AECuO2 (AE112). As the substrate position x increased from 0 mm to 10 mm, the diffraction angle increased, and the c-axis length decreased. This decrease in c-axis length is thought to be due to the replacement of the larger Sr2+ ion with the smaller Ca2+ ion. The sheet resistance also tended to increase as x increased. This indicates that the resistance increases with the addition of Ca to the Sr site in the AE112 crystal structure. These results show that the combinatorial PLD method allows for the continuous acquisition of data with varying composition ratios on a single substrate in a single deposition process. However, the intended AE2CuO3 could not be fabricated because the AE ratio in the thin films was too low.
Future efforts will focus on fabricating thin films by increasing the AE ratio in the targets. The objective is to fabricate AE-Cu-O superconductors by optimizing conditions such as heater temperature and oxygen pressure.