Changqiu Yu

Dr. Changqiu Yu

EE, Hangzhou Dianzi University, Hangzhou, Zhejiang, China
avatar
Co-authors
avatar
Following
avatar
Followers

Research Focus & Metrics

Explore full metrics on Scilit

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
26 June 2023 in Applied Physics Letters
Verified
Journal Article
Open access
PDF file
HFHaodong Fan
Haodong Fan
MJMenghao Jin
Menghao Jin
BWBirui Wu
Birui Wu
MWMingzhang Wei
Mingzhang Wei
JWJiale Wang
Jiale Wang
TZTiejun Zhou
Tiejun Zhou
Ir-CoFeB-based synthetic antiferromagnets (SAFs) are potential candidates as the free layer of the next-generation magnetic tunnel junctions (MTJs) for high speed and density memories due to their perpendicular magnetic anisotropy and strong interlayer exchange coupling. However, the field-free spin–orbit torque (SOT) switching of Ir-CoFeB-based SAFs has rarely been reported, especially in the Co/Ir/CoFeB system with high anti-interference capability and being readily integrated with MTJs. In this paper, SOT-induced magnetization switching and SOT efficiency in Co/Ir/CoFeB SAFs with perpendicular anisotropy and tunable exchange coupling are systemically investigated. A full field-free switching of perpendicular Co/Ir/CoFeB SAFs is realized by depositing them onto crystal miscut Al2O3 substrates, which induce a tilted magnetic anisotropy. Furthermore, by introducing crystalline MgO or amorphous HfO2/SiO2 as the seed layers, the source of the tilted magnetic anisotropy was proved to be from the transverse asymmetry caused by the crystal miscut. Moreover, the crystal miscut enhances the SOT efficiency. The findings provide an approach to reliable field-free switching and high SOT efficiency of Ir-CoFeB-based SAFs for memories as well as logics with low power, fast speed, and high density.
26 January 2021 in IEEE Photonics Technology Letters
Verified
Journal Article
Closed access
CYChangqiu Yu
Changqiu Yu
RNRui Niu
Rui Niu
ZPZhong-Di Peng
Zhong-Di Peng
HLHai Li
Hai Li
Yongming LuoYongming Luo
Yongming Luo
Chunhua DongChunhua Dong
Chunhua Dong
Electric current sensors are widely utilized in high-frequency power and electronic circuits which spread over numerous industries. Here, a current sensor based on the high-Q whispering gallery mode optical capillary microresonator filled with Terfenol-D nanoparticles is experimentally demonstrated. The device shows a peak AC current sensitivity of 5.285 μA Hz -1/2 with a corresponding high accuracy of 0.0009%. It possesses a wide detection frequency bandwidth of approximately 12 MHz and exhibits good linearity, enabling for partial discharge signals detection.
2 April 2021 in Journal of Lightwave Technology
Verified
Journal Article
Closed access
KMKai Ma
Kai Ma
YZYundong Zhang
Yundong Zhang
HSHuaiyin Su
Huaiyin Su
GYGuo Yi
Guo Yi
CYChangqiu Yu
Changqiu Yu
YWYongfeng Wu
Yongfeng Wu
In this paper, we realize tunable Fano and electromagnetically induced transparency (EIT)-like resonances in the outputs of a nested feedback ring resonator. Compared with the traditional add-drop ring resonator, the feedback arm introduces interference between different resonance modes. Using coupled mode theory, we reveal that the output Fano resonances are the interference of discrete modes and continuum modes, whereas the EIT-like resonance only appears in the over-coupled state. We experimentally confirm the two effects using optical fiber ring resonators, finding that the Fano effect can be easily controlled with phase shifts in the feedback arm. Moreover, we achieve the double Fano resonance, which displays an ‘X’ type lineshape utilizing one ring resonator, predicting it to be a good candidate in wavelength monitor. The proposed simple configuration provides a platform to study Fano and EIT-like effect, which is useful in the optical filter, fast and slow light, optical switching, and optical sensing.
30 April 2020 in IEEE Sensors Journal
Verified
Journal Article
Closed access
HSHuaiyin Su
Huaiyin Su
YZYundong Zhang
Yundong Zhang
KMKai Ma
Kai Ma
GYGuo Yi
Guo Yi
YZYongpeng Zhao
Yongpeng Zhao
CYChangqiu Yu
Changqiu Yu
A high-sensitivity optical fiber sensor for low refractive index (RI) measurement is proposed and experimentally demonstrated. It is fabricated by fused splicing a section of multimode fiber (MMF) between two single-mode fibers (SMFs) with a slight offset at two splicing joints, then the MMF is tapered using fused tapering technology. The offset splicing between SMF and MMF can effectively excite more high-order modes. The tapered multimode fiber (TMMF) can enhance the strength of the evanescent field and promote the interplay between the high-order modes and the surrounding medium. The experimental results indicate that the offset value and the waist diameter of the TMMF are two determinants for RI sensitivity enhancement. The RI sensitivity up to 12145 nm/RIU is achieved over the low RI range of 1.3345-1.339. This proposed high-sensitivity fiber-optic RI sensor may provide a low-cost and effective approach for low RI measurement in many chemical and biological applications.
30 March 2020 in Journal of Lightwave Technology
Verified
Journal Article
Closed access
HSHuaiyin Su
Huaiyin Su
YZYundong Zhang
Yundong Zhang
KMKai Ma
Kai Ma
YZYongpeng Zhao
Yongpeng Zhao
CYChangqiu Yu
Changqiu Yu
A tip packaged high-temperature miniature sensor constructed by a suspended-core optical fiber (SCF) is presented and experimentally demonstrated. An SCF with a short length spliced to the single-mode fiber (SMF) is utilized to build the Fabry-Perot interferometer (FPI). A section of SMF acting as a tip package is spliced to the end of the SCF, which gives the sensor immunity of the external refractive index (RI). The test processes of heating up and cooling down are repeated three times to evaluate the repeatability and hysteresis. The arithmetic means temperature sensitivity increases from 9.42 pm/°C to 12.51 pm/°C over the temperature range of 50-800 °C. Moreover, the maximum stability error is 5 °C within the high-temperature 800 °C duration period. This tip packaged sensor with simple fabrication, good repeatability, and good stability within a large dynamic range is advantageous to practical temperature measurement and massive production.
11 August 2023 in Physical Review B
Verified
Journal Article
Closed access
PDF file
BWBirui Wu
Birui Wu
MJMenghao Jin
Menghao Jin
ZSZiji Shao
Ziji Shao
HFHaodong Fan
Haodong Fan
JWJiahong Wen
Jiahong Wen
TZTiejun Zhou
Tiejun Zhou
Current-induced spin-orbit torque (SOT) switching of perpendicular magnetization requires an additional symmetry breaking, calling for modifications of the conventional SOT devices. Here, we have systematically investigated current-induced magnetization switching and dampinglike field in Pt/Co/PtMn trilayer films with a wedged ultrathin antiferromagnetic (AFM) PtMn layer. The symmetry is broken by the effective shape anisotropy in the wedged ultrathin AFM PtMn layer, resulting in the observed field-free SOT switching. Quantitative characterization manifests that the dampinglike (DL) field is boosted up to 30% through wedging the AFM PtMn layer. Additional experiments with in situ magnetic field and micromagnetic simulations indicate the canting of spins caused by the wedge shape accounts for the observed field-free switching and enhancement of SOT efficiency. Our findings provide an easier approach to field-free switching and HDL enhancing for magnetic memory devices with high density and low power consumption.