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Su Y, Zong A, Kogar A, Lu D, Hong SS, Freelon B, Rohwer T, Wang BY, Hwang HY, Gedik N. Delamination-Assisted Ultrafast Wrinkle Formation in a Freestanding Film. Nano Lett 2023. [PMID: 37988604 DOI: 10.1021/acs.nanolett.3c02898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
Freestanding films provide a versatile platform for materials engineering thanks to additional structural motifs not found in films with a substrate. A ubiquitous example is wrinkles, yet little is known about how they can develop over as fast as a few picoseconds due to a lack of experimental probes to visualize their dynamics in real time on the nanoscopic scale. Here, we use time-resolved electron diffraction to directly observe light-activated wrinkling formation in freestanding La2/3Ca1/3MnO3 films. Via a "lock-in" analysis of oscillations in the diffraction peak position, intensity, and width, we quantitatively reconstructed how wrinkles develop on the time scale of lattice vibration. Contrary to the common assumption of fixed boundary conditions, we found that wrinkle development is associated with ultrafast delamination at the film boundaries. Our work provides a generic protocol to quantify wrinkling dynamics in freestanding films and highlights the importance of the film-substrate interaction in determining the properties of freestanding structures.
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Affiliation(s)
- Yifan Su
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Alfred Zong
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
- University of California at Berkeley, Department of Chemistry, Berkeley, California 94720, United States
| | - Anshul Kogar
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Di Lu
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Seung Sae Hong
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Byron Freelon
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Timm Rohwer
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
| | - Bai Yang Wang
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Department of Applied Physics, Stanford University, Stanford, California 94305, United States
- SIMES, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Nuh Gedik
- Massachusetts Institute of Technology, Department of Physics, Cambridge, Massachusetts 02139, United States
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Ling Y, Yu X, Yuan S, He A, Han Z, Du J, Fan Q, Yan S, Xu Q. Flexomagnetic Effect Enhanced Ferromagnetism and Magnetoelectrochemistry in Freestanding High-Entropy Alloy Films. ACS Nano 2023; 17:17299-17307. [PMID: 37643207 DOI: 10.1021/acsnano.3c05255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Freestanding thin films of functional materials enable the tuning of properties via strain and strain gradients, broadening their applications. Here, a systematic approach is proposed to fabricate freestanding CrMnFeCoNi high-entropy alloy (HEA) thin films by pulsed laser deposition using expansion-contraction of NaCl substrates and weak van der Waals interaction of the interface, which form wrinkles with inhomogeneous strain gradients when transferred to a viscous handle. We demonstrate that the nonuniform gradients of external strain (flexomagnetic effect) can induce the partial structural phase transition from FCC to BCC in the wrinkled HEA film, resulting in a 10-fold increase in its room-temperature saturation magnetization compared with the unstrained flat HEA film. Furthermore, after applying an external magnetic field, due to the different electron transfer behavior caused by the electron scattering in wrinkled and flat HEA films, their electrocatalytic magnetic responses showed a diametrically opposite picture. Our work provides a promising strategy for tuning physical and chemical properties via complex strained geometries.
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Affiliation(s)
- Yechao Ling
- School of Physics, Southeast University, Nanjing 211189, China
| | - Xiao Yu
- School of Physics, Southeast University, Nanjing 211189, China
| | - Shijun Yuan
- School of Physics, Southeast University, Nanjing 211189, China
| | - Anpeng He
- School of Physics, Southeast University, Nanjing 211189, China
| | - Zhida Han
- College of Electronic and Information Engineering, Changshu Institute of Technology, Changshu 215500, China
| | - Jun Du
- Department of Physics, Nanjing University, Nanjing 210093, China
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China
| | - Qi Fan
- School of Materials Science and Enigneering, Southeast University, Nanjing 211189, China
| | - Shicheng Yan
- Jiangsu Key Laboratory for Nano Technology, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
| | - Qingyu Xu
- School of Physics, Southeast University, Nanjing 211189, China
- National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210008, China
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