Fen Xue
Postdoctoral Scholar, Electrical Engineering
All Publications
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Thermal optimization of two-terminal SOT-MRAM
JOURNAL OF APPLIED PHYSICS
2024; 136 (1)
View details for DOI 10.1063/5.0211620
View details for Web of Science ID 001260943300007
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The role of magnetic anisotropy in the magnetoresistance of Cr<sub>2</sub>O<sub>3</sub>/Al<sub>2</sub>O<sub>3</sub> thin film antiferromagnets
AIP ADVANCES
2024; 14 (3)
View details for DOI 10.1063/5.0195641
View details for Web of Science ID 001181003200006
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Field-free spin-orbit torque switching assisted by in-plane unconventional spin torque in ultrathin [Pt/Co]N.
Nature communications
2023; 14 (1): 3932
Abstract
Electrical manipulation of magnetization without an external magnetic field is critical for the development of advanced non-volatile magnetic-memory technology that can achieve high memory density and low energy consumption. Several recent studies have revealed efficient out-of-plane spin-orbit torques (SOTs) in a variety of materials for field-free type-z SOT switching. Here, we report on the corresponding type-x configuration, showing significant in-plane unconventional spin polarizations from sputtered ultrathin [Pt/Co]N, which are either highly textured on single crystalline MgO substrates or randomly textured on SiO2 coated Si substrates. The unconventional spin currents generated in the low-dimensional Co films result from the strong orbital magnetic moment, which has been observed by X-ray magnetic circular dichroism (XMCD) measurement. The x-polarized spin torque efficiency reaches up to -0.083 and favors complete field-free switching of CoFeB magnetized along the in-plane charge current direction. Micromagnetic simulations additionally demonstrate its lower switching current than type-y switching, especially in narrow current pulses. Our work provides additional pathways for electrical manipulation of spintronic devices in the pursuit of high-speed, high-density, and low-energy non-volatile memory.
View details for DOI 10.1038/s41467-023-39649-1
View details for PubMedID 37402728
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Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3.
Nature materials
2023
Abstract
Large spin-orbit torques (SOTs) generated by topological materials and heavy metals interfaced with ferromagnets are promising for next-generation magnetic memory and logic devices. SOTs generated from y spin originating from spin Hall and Edelstein effects can realize field-free magnetization switching only when the magnetization and spin are collinear. Here we circumvent the above limitation by utilizing unconventional spins generated in a MnPd3 thin film grown on an oxidized silicon substrate. We observe conventional SOT due to y spin, and out-of-plane and in-plane anti-damping-like torques originated from z spin and x spin, respectively, in MnPd3/CoFeB heterostructures. Notably, we have demonstrated complete field-free switching of perpendicular cobalt via out-of-plane anti-damping-like SOT. Density functional theory calculations show that the observed unconventional torques are due to the low symmetry of the (114)-oriented MnPd3 films. Altogether our results provide a path toward realization of a practical spin channel in ultrafast magnetic memory and logic devices.
View details for DOI 10.1038/s41563-023-01522-3
View details for PubMedID 37012436
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Energy Efficient Computing With High-Density, Field-Free STT-Assisted SOT-MRAM (SAS-MRAM)
IEEE TRANSACTIONS ON MAGNETICS
2023; 59 (3)
View details for DOI 10.1109/TMAG.2022.3224729
View details for Web of Science ID 000963514500004
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2-Terminal, High Density, and Magnetic Field Free SOT-MRAM
IEEE. 2023
View details for DOI 10.1109/TMRC59626.2023.10264011
View details for Web of Science ID 001090519000002
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Performance Benchmarking of Spin-Orbit Torque Magnetic RAM (SOT-MRAM) for Deep Neural Network (DNN) Accelerators
IEEE. 2022: 73-76
View details for DOI 10.1109/IMW52921.2022.9779279
View details for Web of Science ID 000869001800019
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Spin-orbit torques of an in-plane magnetized system modulated by the spin transport in the ferromagnetic Co layer
APL MATERIALS
2021; 9 (10)
View details for DOI 10.1063/5.0048917
View details for Web of Science ID 000754460900001
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Large and robust charge-to-spin conversion in sputtered conductive WTex with disorder
MATTER
2021; 4 (5): 1639-1653
View details for DOI 10.1016/j.matt.2021.02.016
View details for Web of Science ID 000647646400003
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Micro Electric-field Sensors: Principles and Applications
IEEE INDUSTRIAL ELECTRONICS MAGAZINE
2021
View details for DOI 10.1109/MIE.2020.3046226
View details for Web of Science ID 000732888600001
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Tunable spin-orbit torque efficiency in in-plane and perpendicular magnetized [Pt/Co](n) multilayer
APPLIED PHYSICS LETTERS
2021; 118 (4)
View details for DOI 10.1063/5.0034917
View details for Web of Science ID 000630477200002
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Ultrahigh Spin-Orbit Torque Efficiency at Spin Reorientation Transition State in Pt/Co Multilayer
IEEE. 2021
View details for DOI 10.1109/VLSI-TSA51926.2021.9440118
View details for Web of Science ID 000680845500054
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Challenges toward Low-Power SOT-MRAM
IEEE. 2021
View details for DOI 10.1109/IRPS46558.2021.9405127
View details for Web of Science ID 000672563100039
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Drive-Current-Free Switch With Internal Transduction in a Magneto Piezo-Electronic Transistor
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
2020; 67 (4): 3257–66
View details for DOI 10.1109/TIE.2019.2910050
View details for Web of Science ID 000507307000072
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Piezoelectric-Piezoresistive Coupling MEMS Sensors for Measurement of Electric Fields of Broad Bandwidth and Large Dynamic Range
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
2020; 67 (1): 551–59
View details for DOI 10.1109/TIE.2019.2893837
View details for Web of Science ID 000490858500050
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Large voltage control of magnetic anisotropy in CoFeB/MgO/OX structures at room temperature
APL MATERIALS
2019; 7 (10)
View details for DOI 10.1063/1.5101002
View details for Web of Science ID 000501309200002
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Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication.
Micromachines
2019; 10 (6)
Abstract
Taking advantage of good hermeticity, tiny parasitic capacitance, batch mode fabrication, and compatibility with multiple bonding techniques, the glass-silicon composite substrate manufactured by the glass reflow process has great potential to achieve 3D wafer-level packaging for high performance. However, the difference in etching characteristics between silicon and glass inevitably leads to the formation of the undesired micro-protrusions near the silicon-glass interface when preparing a shallow cavity etched around a few microns in the composite substrate. The micro-protrusions have a comparable height with the depth of the cavity, which increases the risks of damages to sensitive structures and may even trigger electrical breakdown, resulting in thorough device failure. In this paper, we studied the characteristics of the chemical composition and etching mechanisms at the interface carefully and proposed the corresponding optimized solutions that utilized plasma accumulation at the interface to accelerate etching and bridge the gap in etching rates between different chemical compositions. Finally, a smooth transition of 131.1 nm was achieved at the interface, obtaining an ideal etching cavity surface and experimentally demonstrating the feasibility of our proposal. The micromachining solution is beneficial for improving the yield and structural design flexibility of higher performance micro-electromechanical systems (MEMS) devices.
View details for DOI 10.3390/mi10060420
View details for PubMedID 31234592
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Two-terminal spin-orbit torque magnetoresistive random access memory
NATURE ELECTRONICS
2018; 1 (9): 508–11
View details for DOI 10.1038/s41928-018-0131-z
View details for Web of Science ID 000454039700014
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Linear Control of Magneto-Electric Effect With Small Electric Fields
IEEE MAGNETICS LETTERS
2016; 7
View details for DOI 10.1109/LMAG.2016.2551694
View details for Web of Science ID 000399976300001
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Electric Field Sensor Based on Piezoelectric Bending Effect for Wide Range Measurement
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
2015; 62 (9): 5730-5737
View details for DOI 10.1109/TIE.2015.2414397
View details for Web of Science ID 000359560800038