Creation of novel cooling devices by simultaneously controlling electric/magnetic dipole orders near the phase transition temperature

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K04229
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Hyogo Prefectural Institute of Technology
• Principal Investigator: Izumi Hirokazu 兵庫県立工業技術センター, その他部局等, 部次長 (70470226)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: multiferroics / electrocaloric effect / PLD / laser assist

Outline of Final Research Achievements

BiFeO3 is known as a multiferroic material that can be used at temperatures above room temperature, and the correlation between polarization and magnetic spin order around the transition temperature was investigated to gain insight into the creation of novel cooling elements through simultaneous control of polarization and magnetic spin order by an electric field.
A BiFeO3 thin film with excellent insulation to which a high electric field can be applied was created by "in-situ laser-assisted irradiation," and it was found that element substitution with La and Al also improved the insulation. It was also found that spontaneous polarization increases when stress is applied to the BiFeO3 thin film. In systems with elemental substitution, the magnetic spin order tends to be slightly reversed upon polarization inversion by an electric field.

Free Research Field

無機材料化学

Academic Significance and Societal Importance of the Research Achievements

本研究では、電場による両者のエントロピー変化の同時制御を用いる新奇冷却素子の創製についての知見を得るため、相転移温度近傍における分極および磁気スピン秩序の相関についての調査を行った。「その場レーザー光援用照射」により高品質な結晶性薄膜が得られたという成果は、原理的に、幅広い材料系に適用することが可能な手法で、その応用範囲は広い。また、これまで元素置換により強磁性を発現させた系で見られていた電場による分極反転と同時に起こる磁気スピン秩序の反転が、わずかではあるが強磁性を発現していない系で見られたことは、より詳細な検証が必要ではあるが、新たな知見としての意義があると考えられる。