Regulation of phase transition and magnetocaloric effect by ferroelectric domains in FeRh/PMN-PT heterojunctions. (1st June 2020)

• Record Type: Journal Article
• Authors: Qiao, Kaiming; Wang, Jianlin; Hu, Fengxia; Li, Jia; Zhang, Cheng; Liu, Yao; Yu, Zibing; Gao, Yihong; Su, Jian; Shen, Feiran; Zhou, Houbo; Bai, Xuedong; Wang, Jing; Franco, Victorino; Sun, Jirong; Shen, Baogen
• Is Part Of: Acta materialia. Volume 191(2020)
• Page Start: 51
• Page End: 59
• Publication Date: 2020-06-01
• Subjects: FeRh film -- Regulation of phase transition -- Magnetocaloric effect -- Ferroelectric domains; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2020.03.028
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The narrow temperature span, Δ T span, of first-order magnetocaloric materials is a serious problem that limits the application as refrigerants. Here we report tunable phase transition and magnetocaloric effect controlled by ferroelectric (FE) domains in FeRh films grown on (001)- and (011)-cut PMN-PT substrates. Adjacent two-step phase transition, and hence significantly broadened Δ T span, has been achieved in FeRh films by utilizing the multi-domain structure of PMN-PT substrates. The results of aberration corrected (ac)-STEM, EELS and EDX analysis revealed that a 3~4 nm buffer layer with AB2 O4 -type spinel structure is naturally formed at the interface, which largely reduces the lattice mismatch between FeRh and PMN-PT and plays a key role for the successful growth of epitaxial (oriented) FeRh film on either (001)- or (011)-oriented PMN-PT. The switched FE domains by electric field govern the phase transition of FeRh films. As a result, regulated entropy change and refrigeration capacity in a wide temperature span have been achieved. On this basis, a feasible magnetic refrigeration cycle facilitated by electric field is designed. The present study provides an experimental basis for expanding the refrigeration temperature span by ferroelectric domain engineering, which is significant for promoting refrigeration application of first-order magnetocaloric materials particularly in micro-devices. Graphical abstracts: Well oriented FeRh thin films with multi domain structure have been successfully grown onto PMN-PT substrates. Ac-STEM, EELS and EDX analysis revealed that a 3~4 nm buffer layer with AB2 O4 -type spinel structure is naturally formed at the interface, which largely reduces the lattice mismatch between FeRh and PMN-PT. The switched FE domains by electric field govern the phase transition of FeRh films. As a result, regulated entropy change and refrigeration capacity in a greatly broadened temperature span have been achieved. Image, graphical abstract