Gang Ni

Fudan University

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H. Sang

China Medical University

Youwei Du

Nanjing University of Information Science and Technology

Hezhu Shao

Wenzhou University

Heyuan Zhu

Fudan University

Bo Peng

University of Cambridge

Hao Zhang

Fudan University

Haibin Zhao

Fudan University

Qingyu Xu

North China University of Water Resources and Electric Power

Yuanfeng Xu

Shandong Jianzhu University

Jing Li

Fudan University

Cooperative Institutions

Fudan University

Chinese Academy of Sciences

Nanjing University

Collaborative Innovation Center of Advanced Microstructures

Zhejiang University

University of Chinese Academy of Sciences

National Laboratory of Solid State Microstructures

Shanghai Jiao Tong University

Beijing Institute of Technology

Beijing University of Posts and Telecommunications

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Quadratic magneto-optical effect in hexagonal non-collinear antiferromagnets

AIP Advances (2021)

Hui Zhao Hong Xia Zirui Zhao Tingli He Gang Ni

Quadratic magneto-optical (MO) effects can be utilized to investigate the spin order in antiferromagnetic (AFM) materials; however, the previously reported studies were all limited in antiferromagnets with collinear AFM order. Here, we develop a phenomenological theory to investigate the quadratic MO effects in hexagonal non-collinear AFM crystals with triangular spin structures. Based on the permittivity tensor up to the second-order in magnetization, we derive the formula to describe the quadratic MO responses and perform numerical calculations to obtain the MO rotation angle for different AFM spin configurations and sample orientations. For the sample with its spin plane lying perpendicular to the surface plane, we have revealed the emergence of quadratic MO response, which exhibits a strong dependence on the light incident angle. The MO rotation angle shows an approximately sinusoidal variation with a periodicity of 180° when the sample is rotated around its surface normal. The size of the MO response and its deviation from the sinusoidal form are analyzed for different values of the second-order permittivity tensor elements. This study provides important insights into the non-collinear AFM spin-induced quadratic MO effect, which may be used as a guidance for optical detections of the non-collinear AFM order, and, in particular, the ultrafast spin dynamics using the optical pump–probe technique.

10.1063/5.0043066

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Citations (1)

Table of Contents

2018 IEEE MTT-S International Wireless Symposium (IWS) (2021)

Wen‐Yan Yin Qiwei Zhan Kai Kang Luo Yuchuan Yanchang Gao

Table (database)

10.1109/iws52775.2021.9499582

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Low frequency Raman spectra of granular CoxAg1 − x films

Nanostructured Materials (1998)

Guangxu Cheng H. Sang Gang Ni H. Chen Youwei Du

10.1016/s0965-9773(98)00150-0

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Citations (1)

Temperature and metal composition dependence of lateral photovoltaic effect in Al-Alq3/SiO2/Si structures

Chinese Optics Letters (2014)

Chao Wang Chao Wang Junqiang Shao Junqiang Shao Zelin Mu Zelin Mu W. Liu Gang Ni

A series of Alx-(Alq3)1-x granular films is prepared on Si wafer with native oxide layer using co-evaporation technique.Large lateral photovoltaic effect (LPE) is observed, with an optimal LPV sensitivity of 75 mV/mm in x = 0.35 sample.The dependence of LPE on temperature and Al composition is investigated, and the possible mechanism is discussed.

10.3788/col201412.040402

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The Hall Effect in Ni0.8Co0.2-SiO2 Granular Film

Acta Physica Sinica (1999)

Gang Ni Lu Jun Xu Qing-Yu H. Sang Du You-Wei

The Hall effect in Ni0.8Co0.2-SiO2 granular films which were fabricated by ion beam sputtering technique was studied. The saturated Hall resistivity reached 6.3μΩ·cm in an applied field of 9.5×105 A/m at room temperature when NiCo volume fraction x is near the metal-insulator transition threshold. The temperature dependence of resistivity in these samples with different NiCo compositions was also investigated. It showed-lg T dependence in low x samples, which gradually showed metallic as x increased. Transmission electron microscopy and vibrating sample magnetometer were used to study the microstructures and magnetic properties, the dependence of transport properties on microstructure was also discussed.

10.7498/aps.48.47

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Study on magnetic property of Fe14Ni86 alloy nanowire array

Journal of Magnetism and Magnetic Materials (2001)

Hao Zhu Shaoguang Yang Gang Ni Dongliang Yu Du You-Wei

Saturation (graph theory)

10.1016/s0304-8853(01)00350-x

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Citations (28)

Nonthermal Ultrafast Optical Control of Magnetization Dynamics by Linearly Polarized Light in Metallic Ferromagnet

Advanced Science (2023)

Jingyu Shi Zirui Zhao Y.D. DAI Jiang He Tao Li

Coherent optical control of the magnetization in ferromagnetic (FM) mediums using ultrafast nonthermal effect paves a promising avenue to improve the speed and repetition rate of the magnetization manipulation. Whereas previously, only heat-induced or helicity-dependent magnetization dynamics are demonstrated in metallic ferromagnets. Here, the linearly-polarized light control of magnetization is demonstrated in FM Co coupled with ferroelectric (FE) BiFeO3 by tuning the light polarization direction. It is revealed that in the Co/BiFeO3 heterostructure excited by femtosecond laser pulses, the magnetization precession amplitude follows a sinusoidal dependence on the laser polarization direction. This nonthermal control of coherent magnetization rotation is attributed to the optical rectification effect in the BiFeO3 layer, which yields a FE polarization depending on the light polarization, and the subsequent modulation of magnetic energy in Co by the electrostriction-induced strain. This work demonstrates an effective route to nonthermally manipulate the ultrafast magnetization dynamics in metallic ferromagnets.

Magnetization dynamics

10.1002/advs.202205903

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Magnetization reversal mechanism of magnetic tunnel junctions

Chinese Physics (2002)

Liu Cun-Ye Jian Li Yue Wang Jianyong Chen Xu Qing-Yu

Using the ion-beam-sputtering technique, we have fabricated Fe/Al2O3/Fe magnetic tunnelling junctions (MTJs). We have observed double-peaked shapes of curves, which have a level summit and a symmetrical feature, showing the magnetoresistance of the junction as a function of applied field. We have measured the tunnel conductance of MTJs which have insulating layers of different thicknesses. We have studied the dependence of the magnetoresistance of MTJs on tunnel conductance. The microstructures of hard- and soft-magnetic layers and interfaces of ferromagnets and insulators were probed. Analysing the influence of MJT microstructures, including those having clusters or/and granules in magnetic and non-magnetic films, a magnetization reversal mechanism (MRM) is proposed, which suggests that the MRM of tunnelling junctions may be explained by using a group-by-group reversal model of magnetic moments of the mesoscopical particles. We discuss the influence of MTJ microstructures, including those with clusters or/and granules in the ferromagnetic and non-magnetic films, on the MRM.

Magnetization reversal

Tunnel magnetoresistance

10.1088/1009-1963/11/1/314

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Transport properties, microstructures and domain observation in Ag 1-x -(Ni 0.8 Co 0.2 ) x granular films

Scripta Materialia (2001)

Gang Ni Xu Qing-Yu Xiao-Bo Yin H. Sang Tang Shaolong

Superparamagnetism

10.1016/s1359-6462(01)00841-7

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The conflicting role of buckled structure in phonon transport of 2D group-IV and group-V materials

Nanoscale (2017)

Bo Peng Dequan Zhang Hao Zhang Hezhu Shao Gang Ni

Controlling heat transport through material design is one important step toward thermal management in 2D materials. To control heat transport, a comprehensive understanding of how structure influences heat transport is required. It has been argued that a buckled structure is able to suppress heat transport by increasing the flexural phonon scattering. Using a first principles approach, we calculate the lattice thermal conductivity of 2D mono-elemental materials with a buckled structure. Somewhat counterintuitively, we find that although 2D group-V materials have a larger mass and higher buckling height than their group-IV counterparts, the calculated κ of blue phosphorene (106.6 W mK-1) is nearly four times higher than that of silicene (28.3 W mK-1), while arsenene (37.8 W mK-1) is more than fifteen times higher than germanene (2.4 W mK-1). We report for the first time that a buckled structure has three conflicting effects: (i) increasing the Debye temperature by increasing the overlap of the pz orbitals, (ii) suppressing the acoustic-optical scattering by forming an acoustic-optical gap, and (iii) increasing the flexural phonon scattering. The former two, corresponding to the harmonic phonon part, tend to enhance κ, while the last one, corresponding to the anharmonic part, suppresses it. This relationship between the buckled structure and phonon behaviour provides insight into how to control heat transport in 2D materials.

10.1039/c7nr00838d

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Citations (134)