11 results on '"Tianrui Zhai"'
Search Results
2. Manipulation of crystalline structure, magnetic performance, and topological feature in Mn3Ge films
- Author
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Tianrui Zhai, Jinxiang Deng, Xue Chen, Chen Zhang, Qianqian Yang, Lei Liu, Xiaolei Wang, Dong Pan, and Hui-Xiong Deng
- Subjects
Materials science ,Spintronics ,Magnetoresistance ,Physics ,QC1-999 ,General Engineering ,Fermi surface ,Topology ,Condensed Matter::Materials Science ,Tetragonal crystal system ,Ferromagnetism ,Hall effect ,Density of states ,Antiferromagnetism ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,TP248.13-248.65 ,Biotechnology - Abstract
The Mn3X (where X = Ga, Ge, Sn, etc.) compounds have appealing prospects for spintronic applications due to their various crystal structures and magnetic properties for the design of reliable high-density memories. However, controlled growth of high-quality Mn3X thin films remains challenging in material science. Here, we reported the controlled film growth of Heusler alloy Mn3Ge, which could crystallize in respective tetragonal and hexagonal structures. The tetragonal D022-type Mn3Ge film exhibits strong perpendicular ferromagnetic anisotropy, while the hexagonal D019-type Mn3Ge film indicates non-collinear triangular antiferromagnetic order. From our experimental observations of structure characterizations, magnetic properties, anomalous Hall effect, and magnetoresistance measurements, we realized the manipulation of spin orientations and topological features. Majority/minority spin polarized Fermi surface and density of states of both tetragonal and hexagonal Mn3Ge structures were investigated by density functional theory calculations. Our work not only opens up technology routes toward the development of Mn3X-based devices for applications in topological spintronics and spin-torque memories but also leads to engineer the physical properties for fundamental study.
- Published
- 2021
3. Distributed feedback lasing in a metallic cavity
- Author
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Tianrui Zhai, Fei Tong, Fengzhao Cao, Lianze Niu, Xinping Zhang, Songtao Li, and Meng Wang
- Subjects
Distributed feedback laser ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Nanophotonics ,02 engineering and technology ,Grating ,Photoresist ,021001 nanoscience & nanotechnology ,01 natural sciences ,Interference lithography ,010309 optics ,Optics ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Lasing threshold ,Diffraction grating ,Plasmon - Abstract
Distributed feedback (DFB) lasing is observed in a metallic cavity, which consists of a gold grating and a polymer membrane. The gold grating is prepared by evaporating a 25 nm thin film of gold on the photoresist grating fabricated by interference lithography. A 150 nm thick polymer membrane is directly attached on the gold grating, forming a suspended membrane supported by the grating ridge. The assembly method decreases the metallic contact area, which makes the mode more photonic and thereby reduces the ohmic loss of the metal. Low threshold DFB lasing can be achieved when the sample is optically pumped. The fabrication technique provides a facile way to realize plasmonic DFB polymer lasers.
- Published
- 2017
4. Multi-wavelength lasing in a beat structure
- Author
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Tianrui Zhai, Songtao Li, Fei Tong, Xiaofeng Wu, Xinping Zhang, and Meng Wang
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Physics::Optics ,Beat (acoustics) ,02 engineering and technology ,Grating ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Interference lithography ,law.invention ,010309 optics ,Superposition principle ,Wavelength ,Optics ,law ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Lithography ,Lasing threshold - Abstract
Multi-wavelength polymer lasers are produced with one-dimensional beat structures fabricated with multiple gratings at the same substrate location using interference lithography. As a distributed feedback cavity, the beat structure is equivalent to a linear superposition of multiple grating cavities. Each emission wavelength is determined by the corresponding grating cavity, which implies that interaction between different cavities is very weak. For a beat structure consisting of three gratings, emission peaks at 558 nm, 565 nm, and 569 nm originate from 350-nm, 362-nm, and 374-nm cavities, with thresholds of 14.5 μJ/cm2, 15.0 μJ/cm2, and 13.5 μJ/cm2, respectively. This technique provides an alternative way to design compact polymer lasers.
- Published
- 2016
5. Dual-wavelength polymer laser based on an active/inactive/active sandwich-like structure
- Author
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Songtao Li, Yanbin Ma, Jinxiang Deng, Tianrui Zhai, Xiaofeng Wu, Meng Wang, Fei Tong, and Xinping Zhang
- Subjects
chemistry.chemical_classification ,Spin coating ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Stacking ,02 engineering and technology ,Polymer ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,law.invention ,010309 optics ,Wavelength ,chemistry ,Quantum dot laser ,law ,0103 physical sciences ,Optoelectronics ,0210 nano-technology ,business ,Refractive index ,Waveguide - Abstract
Dual-wavelength laser emission is achieved by using an active/inactive/active sandwich-like structure, which can be conveniently fabricated using spin coating technique. Poly [(9, 9-dioctylfluorenyl-2, 7-diyl)-alt-co-(1, 4-benzo-(2, 1′, 3) -thiadiazole)] and polyvinyl alcohol are employed as the active and the inactive materials, respectively. Two laser wavelengths are simultaneously observed, which are attributed to the difference of the surrounding refractive index of two active waveguides in the sandwich-like structure. Each wavelength is controlled by the respective waveguide structure, meaning that multi-wavelength laser can be designed by stacking the active/inactive layer pair. These results provide more flexibility to design compact laser sources.
- Published
- 2016
6. Free-standing membrane polymer laser on the end of an optical fiber
- Author
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Xinping Zhang, Li Wang, Tianrui Zhai, Li Chen, Yimeng Wang, Songtao Li, and Yujie Hu
- Subjects
Distributed feedback laser ,Materials science ,Optical fiber ,Physics and Astronomy (miscellaneous) ,business.industry ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,law.invention ,010309 optics ,Optical pumping ,Membrane ,Optics ,law ,Fiber laser ,0103 physical sciences ,0210 nano-technology ,business ,Plastic optical fiber ,Lasing threshold - Abstract
One- and two-dimensional distributed feedback cavities were constructed on free-standing polymer membranes using spin-coating and lift-off techniques. Low threshold lasing was generated through feedback amplification when the 290-nm membrane device was optically pumped, which was attributed to the strong confinement mechanism provided by the active waveguide layer without a substrate. The free-standing membrane polymer laser is flexible and can be transplanted. Single- and dual-wavelength fiber lasers were achieved by directly attaching the membrane polymer laser on the optical fiber end face. This technique provides potential to fabricate polymer lasers on surfaces with arbitrary shapes.
- Published
- 2016
7. Direct writing of flexible bimetallic nanoparticles for hybrid plasmon response
- Author
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Xinping Zhang, Tianrui Zhai, Yonglu Wang, Hongmei Liu, and Zhiyang Xu
- Subjects
Nanostructure ,Random laser ,Materials science ,Nanolithography ,Physics and Astronomy (miscellaneous) ,Physics::Optics ,Nanoparticle ,Particle ,Nanotechnology ,Bimetallic strip ,Plasmon ,Silver nanoparticle - Abstract
Two types of bimetallic nanoparticle are constructed on soft substrates via a laser-induced transfer technique. One particle is a physical mixture with distinct gold and silver nanoparticles, while the other is a gold-silver alloy nanoparticle. Different hybrid plasmon responses can be achieved by these nanoparticles, which can be attributed to electromagnetic interactions between gold and silver. Both nanostructures can be fabricated using one or two ultraviolet laser pulses. Also, the stability of the spectra of these nanoparticles remains robust when the substrate is stretched and bended. These particles may provide an alternative way to investigate plasmonic sensors and random laser devices.
- Published
- 2014
8. Blue photoluminescence enhancement in laser-irradiated 6H-SiC at room temperature
- Author
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Yijian Jiang, Yan Wu, Zhenyuan Lin, Lingfei Ji, and Tianrui Zhai
- Subjects
Photoluminescence ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Wide-bandgap semiconductor ,Photon energy ,medicine.disease_cause ,Laser ,law.invention ,law ,medicine ,Optoelectronics ,Irradiation ,Luminescence ,business ,Ultraviolet ,Surface states - Abstract
Blue photoluminescence (PL) of 6H-SiC irradiated by an ultraviolet laser can be observed at room temperature in dark condition. PL spectra with Gaussian fitting curve of the irradiated SiC show that blue luminescence band (∼440 nm) is more pronounced than other bands. The blue PL enhancement is the combined result of the improved shallow N-donor energy level and the unique surface state with Si nanocrystals and graphene/Si composite due to the effect of photon energy input by the short-wavelength laser irradiation. The study can provide a promising route towards the preparation of well-controlled blue photoluminescence material for light-emitting devices.
- Published
- 2014
9. Gain- and feedback-channel matching in lasers based on radiative-waveguide gratings
- Author
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Tianrui Zhai and Xinping Zhang
- Subjects
Materials science ,Photoluminescence ,Physics and Astronomy (miscellaneous) ,business.industry ,Physics::Optics ,Resonance ,Grating ,Laser ,Waveguide (optics) ,law.invention ,Optics ,law ,Radiative transfer ,Optoelectronics ,Emission spectrum ,business ,Diffraction grating - Abstract
Angle-resolved emission spectroscopy is employed to investigate the distributed feedback (DFB) mechanisms in active waveguide grating structures with the DFB cavity consisting of a dielectric grating on an active waveguide layer. Laser emission can be achieved at the perfect matching between the resonance mode and the gain spectrum of the DFB cavity. This requires vertical surface-emitting resonance mode and its overlap with the peak of the gain spectrum that is determined by the photoluminescence spectrum of the active medium and the structural parameters of the DFB cavity.
- Published
- 2012
10. Hybrid metallic photonic crystals with higher-order coupling processes
- Author
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Zhaoguang Pang, Tianrui Zhai, and Xinping Zhang
- Subjects
Materials science ,business.industry ,Guided-mode resonance ,Physics::Optics ,General Physics and Astronomy ,Grating ,Interference lithography ,Condensed Matter::Materials Science ,Optics ,Colloidal gold ,Optoelectronics ,Physics::Atomic Physics ,Surface plasmon resonance ,business ,Diffraction grating ,Plasmon ,Photonic crystal - Abstract
Hybrid metallic photonic crystals (MPCs) combine the orderly arranged grating structures and the disordered gold nanostructures, where the gratings are fabricated by interference lithography on a layer of waveguide and the isolated gold nanoislands arranged randomly in the grating grooves are produced using solution-processible gold nanoparticles. Strong coupling between multiple higher-order resonance modes of the waveguide grating structures and particle plasmon resonance of the isolated gold nanoislands has been observed in the visible spectral range. This technique actually realizes fabrication of the waveguide grating structures and the plasmonic gold nanostructures separately. In this way, the plasmonic resonance of the gold nanostructures is not determined by the dimensions of the grating lines anymore. Thus, the grating structures can be fabricated easily with a period of microns, whereas the size of the gold nanostructures can be controlled flexibly by changing the colloidal concentration and the...
- Published
- 2011
11. A Dnv point group structure possessing complete band gap based on gradual heterostructure and self-simulating sphere
- Author
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Dahe Liu, Tianrui Zhai, Zhaona Wang, Xiangdong Zhang, Jing Zhou, and Rongkuo Zhao
- Subjects
Materials science ,Nanostructure ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,business.industry ,Band gap ,Heterojunction ,Crystal structure ,Optoelectronics ,Point (geometry) ,Direct and indirect band gaps ,business ,Refractive index ,Photonic crystal - Abstract
A structure with Dnv point group was fabricated by compounding a gradual heterostructure and a self-simulating sphere. The gradual heterostructure has two-dimensional omnidirectional band gap and the self-simulating sphere makes it possess a complete band gap. The experimental results were explained by theoretical analysis. This kind of structure can be implemented using low refractive index materials.
- Published
- 2008
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