Article
Engineering, Electrical & Electronic
Dingbin Huang, Dustin Lattery, Xiaojia Wang
Summary: The TR-MOKE methodology is a powerful tool for detecting magnetization dynamics with superb temporal and spatial resolutions. This article highlights recent advances in TR-MOKE metrology and its applications in capturing magnetization dynamics in technologically important spintronic materials, with a focus on research activities at the University of Minnesota.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Nanoscience & Nanotechnology
Guoqiang Du, Yamei Zuo, Na Liu, Zhifeng Liu, Lin Zhang, Weiwei Zhang
Summary: This study comprehensively investigated the transverse magneto-optical Kerr effect (TMOKE) with gas sensing ability by directly patterning a subwavelength periodic nanogroove on a cobalt film. High-amplitude TMOKE was observed, which was 243 times as intense as that of a smooth film. The physical mechanism responsible for this improvement was elucidated by activating surface plasmon resonance at the gas-cobalt interface.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Luu Ly Pham Ngoc, Kyuhwe Kang, Gyung-Min Choi
Summary: This study utilizes time-resolved magneto-optical Kerr effect measurement and pump-probe technique to investigate the thermal characterization of various materials, determining their anisotropic thermal conductivity and providing strong support for materials thermal management.
Article
Optics
Jiamin Liu, Wenqi Gong, Lei Li, Song Zhang, Jinlong Zhu, Rong Chen, Hao Jiang, Shiyuan Liu
Summary: This paper presents an in-situ characterization method based on Mueller-matrix ellipsometry for investigating the longitudinal MO Kerr effects occurring in subwavelength thick ferromagnetic films. The proposed method allows reliable capture of the weak MO Kerr response signal of the ferromagnetic films with high repeatability precision better than 0.0002.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Na Wang, Jun Chen, Ning Ding, Huimin Zhang, Shuai Dong, Shan -Shan Wang
Summary: In this study, the interesting magnetic order and properties of monolayer RuF4 are revealed using relativistic density functional theory. The material exhibits weak ferromagnetism and a prominent magneto-optical Kerr effect due to the antisymmetric Dzyaloshinskii-Moriya interaction and single-ion anisotropy. Furthermore, a uniaxial strain induces ferroelastic switching and in-plane rotation of spin direction, leading to strong intrinsic magnetoelasticity. This work not only suggests a new direction for two-dimensional magnetic materials, but also provides insights for future devices based on antiferromagnetic magnetoelastic or magneto-optical materials.
Article
Chemistry, Multidisciplinary
Jing Chen, Guohua Wu, Ping Gu, Yumei Tang, Chun Yang, Zhendong Yan, Chaojun Tang, Zhengqi Liu, Fan Gao, Pinggen Cai
Summary: The study focuses on enhancing the transverse magneto-optical Kerr effect (TMOKE) of ultra-thin magnetic dielectric films, achieved through the excitation of strong magnetic resonances due to plasmonic hybridization between Au nanowires and substrate. The coupled system forms two strong magnetic resonances leading to a significant TMOKE signal increase in 30 nm thick ultra-thin magnetic dielectric films, showing potential applications in nanophotonics, magnonics, and spintronics.
Article
Chemistry, Physical
Weiwei Zhang, Guoqiang Du, Hongming Chen, Kang An
Summary: Enhancement of transverse magneto-optical Kerr effects (T-MOKEs) based on surface plasmon resonance has gained widespread attention due to its high sensitivity. However, most studies focus on prism-based magnetoplasmonic structures or architectures that combine noble metal lattice and ferromagnetic layer, hindering device fabrication, miniaturization, and integration into a microfluidic sensing configuration. In this study, we propose a single Co6Ag94 ferromagnetic-metal layer with a square nanopore array system, which exhibits a significantly higher T-MOKE magnitude (51 times) compared to a smooth film, and has the potential to detect gaseous analytes. The proposed system is suitable for early environmental monitoring of gaseous media and provides an accessible pathway for the design of magneto-optical sensors.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Applied
C. Papusoi, T. Le, R. Admana, P. Mani, M. Desai
Summary: Vertical exchange coupling between adjacent layers in a magnetic multilayer has a significant impact on the magnetization reversal mechanism. Through time-resolved magneto-optic Kerr effect (TRMOKE), the study evaluated the vertical exchange coupling energy per unit film surface and found that two different spin models offered similar values for the exchange coupling energy under certain conditions.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Ning Ding, Kunihiro Yananose, Carlo Rizza, Feng-Ren Fan, Shuai Dong, Alessandro Stroppa
Summary: We studied the magneto-optical Kerr effect (MOKE) in a two-dimensional heterostructure CrI3/In2Se3/CrI3 using density functional theory calculations and symmetry analysis. The mirror and time-reversal symmetries are broken by the spontaneous polarization in the In2Se3 ferroelectric layer and the antiferromagnetic ordering in the CrI3 layers, thereby activating MOKE. Our results demonstrate that the Kerr angle can be reversed by either the polarization or the antiferromagnetic order parameter. This suggests that ferroelectric and antiferromagnetic 2D heterostructures could be utilized for compact information storage devices, with the information encoded by the two ferroelectric or the two time-reversed antiferromagnetic states and read optically via MOKE.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Physics, Multidisciplinary
Mansoureh Amanollahi, Mehdi Zamani
Summary: In this paper, a novel structure composed of an all-magneto-optical periodic grating is presented to enhance the transverse magneto-optical Kerr effect (TMOKE), which does not require the use of noble metals. The proposed structure can be utilized for bio-sensing applications by detecting changes in the refractive index of the analyte medium through monitoring of the TMOKE. The advantage of our idea lies in the simultaneous operation of the magneto-optic layer as a sensing layer, leading to extreme TMOKE in a magneto-optical grating.
Article
Physics, Applied
Takeshi Ogasawara, Akinobu Yamaguchi
Summary: The frequency dependent resonance of magnetic vortex core gyration in micrometer sized permalloy squares was observed using a time-resolved magneto-optical Kerr microscope. The study utilized pulsed semiconductor lasers as a light source and a speckle reducer for uniform and efficient laser illumination. The results showed that the flatness of the underlayer strongly influences the gyration motion.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
M. Jovicevic-Klug, P. Jovicevic-Klug, J. McCord, B. Podgornik
Summary: This study demonstrates the potential of using MOKE microscopy to analyze the microstructure and stress state of martensitic steels, without the need for chemical etching, and even achieving accurate volumetric fraction estimation of retained austenite. By combining MOKE microscopy with other techniques, the residual stress state of steel can be accurately determined, and significant reduction in residual stresses can be achieved through deep cryogenic treatment, providing valuable insights for steel properties research.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Physics, Applied
Dedalo Sanz-Hernandez, Luka Skoric, Miguel Angel Cascales-Sandoval, Amalio Fernandez-Pacheco
Summary: Magneto-optical techniques have been developed as key tools for characterizing magnetic effects at the nanoscale. In this study, the researchers introduce the dark-field magneto-optical Kerr effect (DFMOKE), a technique specifically designed for characterizing three-dimensional magnetic nanostructures. They demonstrate the principles of DFMOKE and modify a standard focused MOKE magnetometer to perform measurements. Finally, they showcase the power of DFMOKE by detecting the independent magnetic switching of a single tilted 3D nanowire and a magnetic thin film that surrounds it.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Multidisciplinary Sciences
Michihiko Yamanouchi, Yasufumi Araki, Takaki Sakai, Tetsuya Uemura, Hiromichi Ohta, Jun'ichi Ieda
Summary: In a ferromagnetic Weyl metal, a large effective magnetic field exerted on a magnetic domain wall by current has been reported. The ratio of the effective magnetic field to current density shows a nonmonotonic temperature dependence and surpasses the ratios of conventional spin-transfer torques and spin-orbit torques. This enhancement is well described by the topological Hall torque, which is exerted on the domain wall by Weyl electrons emerging around Weyl points under an applied electric field. The ratio of the effective magnetic field arising from the topological Hall torque to current density is over one order of magnitude higher than that originating from spin-transfer torques and spin-orbit torques in metallic systems, indicating that the topological Hall torque may provide a more energy-efficient way to manipulate magnetization in spintronics devices.
Article
Optics
Weiwei Zhang, Haizi Yao, Yao Lu
Summary: The introduction of a magnetic component to the surface plasmon resonance structure enhances the detection limit for small molecules at low concentrations. In this study, a magneto-optical surface plasmonic resonance detector was designed to detect glucose concentrations. The detector showed high sensitivity and accuracy, making it a promising alternative for analyte detection in aqueous environments.
Article
Chemistry, Multidisciplinary
Adam O'Neill, Sharidya Rahman, Zhen Zhang, Peggy Schoenherr, Tanju Yildirim, Bo Gu, Gang Su, Yuerui Lu, Jan Seidel
Summary: We demonstrate that the structural gradients found in strained nanoscale wrinkles in Cr2Ge2Te6 (CGT) can significantly increase the transition temperature (Tc), which is a key obstacle in using van der Waals materials for spintronic applications. This finding is supported by experimental evidence and ab initio studies, providing insights into the mechanism of enhanced magnetism and Tc.
Article
Materials Science, Multidisciplinary
Yu-Hong Lai, Pao -Wen Shao, Chang-Yang Kuo, Cheng-En Liu, Zhiwei Hu, Chen Luo, Kai Chen, Florin Radu, Yong-Jyun Wang, Junding Zheng, Chungang Duan, Chun-Fu Chang, Li Chang, Yi-Chun Chen, Sang-Wook Cheong, Ying-Hao Chu
Summary: This study investigates the modulation of magnetic and electric orders in magnetoelectric materials through quasi-static mechanical strain. It is found that mechanical bending can significantly enhance the magnetization of Cr2O3 film and adjust its electric polarization and magnetoelectric coupling. This work provides a comprehensive understanding of the relationship between strain and magnetic and electrical behaviors and opens new possibilities for combining magnetoelectric materials with flexible substrates.
Article
Chemistry, Multidisciplinary
Cam-Phu Thi Nguyen, Peggy Schoenherr, Jan Seidel
Summary: The functionality of domain walls and other topological defects in ferroelectrics is being extensively studied for applications in electronic devices. This study presents an in-depth investigation of the nanomechanical properties at 90° domain walls and adjacent domains in single-crystalline lead titanate (PbTiO3) using various AFM-based methods. Significant variations in elastic moduli are observed at 90° domain walls, extending up to approximately 100 nm into the domain areas. AFM nanoindentation is also used to measure local domain wall hardness and deformation energies. These findings have implications for the design of ferroelectric domain wall functionality that incorporates the intrinsic elastic compliance of a domain wall.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Environmental
Min Jun Choi, Seok Woo Lee, Minwoo Lee, So Jeong Shin, Moonyong Kim, Gyeong G. Jeon, Sang Eun Yoon, Fan Xiangyang, Bo Ram Lee, Jan Seidel, Jae Sung Yun, Dong Wook Chang, Jong H. Kim
Summary: Indoor-light harvesting-technology based on perovskite solar cells has shown promising performance in low-intensity indoor light environments. By controlling interfacial dipoles through the use of different polar layers, the charge recombination in perovskite solar cells is effectively reduced, leading to higher power conversion efficiency. These findings contribute to the development of perovskite photovoltaic mini-modules for indoor applications.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Optics
Xu Liu, Bolin Zheng, Lei Shi, Shujie Zhou, Jiangtao Xu, Ziheng Liu, Jae Sung Yun, Eunyoung Choi, Meng Zhang, Yinhua Lv, Wen-Hua Zhang, Jialiang Huang, Caixia Li, Kaiwen Sun, Jan Seidel, Mingrui He, Jun Peng, Xiaojing Hao, Martin Green
Summary: This study presents a facile approach for doping spiro-OMeTAD hole-transport materials using a low-cost alkylthiol additive DDT. The incorporation of DDT allows for a more efficient and controllable doping process with reduced duration. Coordination between DDT and LiTFSI increases the dopant concentration, enhances the structural integrity of the material, and improves device performance under wetting, heat, and light stress.
Article
Multidisciplinary Sciences
Pao-Wen Shao, Yi-Xian Wu, Wei-Han Chen, Mojue Zhang, Minyi Dai, Yen-Chien Kuo, Shang-Hsien Hsieh, Yi-Cheng Tang, Po-Liang Liu, Pu Yu, Yuang Chen, Rong Huang, Chia-Hao Chen, Ju-Hung Hsu, Yi-Chun Chen, Jia-Mian Hu, Ying-Hao Chu
Summary: Authors have discovered tuneable self-assembled nanostructures in the SnO2:NiO system, which extends the design of self-assembled oxides for practical applications in optoelectronics. Self-assembled systems have recently attracted attention for their ability to display a wide range of phase morphologies in nanocomposites. By controlling their concentration, researchers have created tunable self-assembled nanostructures, confirmed through TEM-energy-dispersive X-ray spectroscopy. Phase-field simulations have been used to understand 3D microstructure formation and predict microstructure morphologies in SnO2:NiO nanocomposites of other concentrations. Additionally, significantly enhanced photovoltaic properties have been demonstrated in a bicontinuous SnO2:NiO nanocomposite.
NATURE COMMUNICATIONS
(2023)
Correction
Multidisciplinary Sciences
Pao-Wen Shao, Yi-Xian Wu, Wei-Han Chen, Mojue Zhang, Minyi Dai, Yen-Chien Kuo, Shang-Hsien Hsieh, Yi-Cheng Tang, Po-Liang Liu, Pu Yu, Yuang Chen, Rong Huang, Chia-Hao Chen, Ju-Hung Hsu, Yi-Chun Chen, Jia-Mian Hu, Ying-Hao Chu
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Weigao Han, Shilin Wu, Fang Dong, Weiliang Han, Yinghao Chu, Linghui Su, Zhicheng Tang
Summary: In this study, 3-dimensional ordered macroporous and mesoporous SiO2 was used as a nanoreactor to protect active sites from SO2 erosion in the catalytic combustion of benzene. Co3O4 nanoparticles were successfully confined in the macroporous and mesoporous channels, showing superior sulfur and water resistance. DFT calculations confirmed the high SO2 adsorption energy of the Co-Si catalyst and the low SO2 adsorption energy of the SiO2 nanoreactor, indicating their effectiveness in protecting active sites from SO2 erosion.
Article
Nanoscience & Nanotechnology
Tongtong Huang, Yingjie Lyu, Huaixun Huyan, Jinyang Ni, Sahar Saremi, Yujia Wang, Xingxu Yan, Di Yi, Qing He, Lane W. W. Martin, Hongjun Xiang, Xiaoqing Pan, Pu Yu
Summary: The ferromagnetism in LaCoO3 thin films can be modulated by varying the oxygen pressure during thin-film growth. The magnetization of the samples is not influenced by the cobalt valence state and perovskite crystalline structure, but mainly determined by the tetragonal distortion induced by tensile strain, which modifies the orbital occupancy and leads to a low-spin to high-spin transition. This work provides important insights into the understanding of exotic ferromagnetism in LaCoO3 thin films and suggests a promising strategy for designing electronic states in complex oxides through cation-stoichiometry engineering.
ADVANCED ELECTRONIC MATERIALS
(2023)
Review
Multidisciplinary Sciences
Lin Hao, Di Yi, Meng Wang, Jian Liu, Pu Yu
Summary: In recent years, research on iridates has made significant progress, uncovering numerous emergent phenomena, intriguing physics, and interesting functionalities. Artificial structures based on iridates have been crucial due to their high flexibility and tunability in lattice symmetry, chemical composition, and crystal dimensionality. This article provides an overview of recent advancements in iridate-based artificial structures, including key concepts, findings in SrIrO3/SrTiO3 superlattices and heterostructures with magnetic oxides, and their response to external electric-field stimuli. It concludes with a discussion on existing challenges and promising future directions in this exciting field.
FUNDAMENTAL RESEARCH
(2023)
Article
Nanoscience & Nanotechnology
Jia-Wei Chen, Yun-Guan Wei, Hung-Yang Lo, Sicheng Lu, Yi-Che Chen, Chi-Fong Lei, Po-Liang Liu, Pu Yu, Nien-Ti Tsou, Akira Yasuhara, Wen-Wei Wu, Ying-Hao Chu
Summary: Quasi van der Waals epitaxy is a method to construct combinations of 2D and 3D materials. The interface structure and mechanical robustness of metal/muscovite systems have been studied. The anisotropic thermal expansion and thermal stress tolerance in the silver/muscovite heteroepitaxy have been discovered and demonstrated. The electrothermal and photothermal methods show fast response to thermal stress, proving the interface robustness.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Runfa Feng, Wei Wang, Changhua Bao, Zichun Zhang, Fei Wang, Hongyun Zhang, Junjie Yao, Yong Xu, Pu Yu, Shuai-Hua Ji, Chen Si, Shuyun Zhou
Summary: This study reports the selective growth of monolayer TaTe2 films with different phases and superstructures by controlling the growth temperature and post-growth annealing treatment. The different electronic structures of 1H-TaTe2 and 1T-TaTe2 films are revealed through experimental measurements and theoretical calculations. The transition from a root 19x root 19 superstructure to a new 2 x 2 superstructure is observed in the annealed 1H-TaTe2 film.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Eduardo Lupi, Robert B. Wexler, Derek Meyers, Anton Zahradnik, Yizhe Jiang, Sandhya Susarla, Ramamoorthy Ramesh, Lane W. Martin, Andrew M. Rappe
Summary: Complex-oxide superlattices with precise unit-cell structures provide a pathway to various emergent phenomena. In this study, relaxor-like behavior is observed in superlattices of ferroelectric and dielectric materials. The behavior is influenced by the periodicity and shape of the superlattice.
ADVANCED MATERIALS
(2023)
Article
Physics, Multidisciplinary
Zishen Tian, Michael Xu, Jieun Kim, Hao Pan, Djamila Lou, Xiaoxi Huang, James M. Lebeau, Lane W. Martin
Summary: Superlattices of [BaTiO3]m/[BaZrO3]n (m, n = 4-12) are used to demonstrate the fabrication and control of an artificial relaxor. Experimental results show the successful production of high-quality heterostructures. The study reveals a transition in the dielectric properties of the materials as the BaTiO3 layer thickness decreases.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
P. -C. Chiang, S. C. Lin, C. -Y. Chiang, C. -S. Ku, S. W. Huang, J. M. Lee, Y. -D. Chuang, H. J. Lin, Y. F. Liao, C-M. Cheng, S. C. Haw, J. M. Chen, Y. -H. Chu, T. H. Do, C. -W. Luo, J. -Y. Juang, K. H. Wu, Y. -W. Chang, J. -C. Yang, J. -Y. Lin
Summary: Recent studies have shown that quasi-two-dimensional (quasi-2D) systems with atomic monolayer or few-layer architecture exhibit unprecedented physical properties that challenge conventional theories in condensed matter physics. In this study, it was found that the infinite layer SrCuO2 (SCO) can exhibit an unexpected metallic state when grown on SrTiO3 substrates. This metallic state does not conform to the traditional Landau's Fermi liquid paradigm. Furthermore, it was discovered that the hole doping in SCO does not occur at the interfaces between SCO and STO, but rather from transient layers within the SCO slab.
