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Welcome to " BLS & Microwave Magnetism" Lab

       The mainly topics of our teams are: Brillouin light scattering, Magnons-Photons interactions, Magnetic anisotropy and spin dynamics in magnetic thin films, and microwave measurement methods for GHz properties of materials. Details as follow:

  • Brillouin light scattering
  • Magnons-Photons interactions
  • Magnetic anisotropy and spin dynamics in magnetic thin films
  • Study the quantum chaos with microwaves
  • Microwave imaging and near field magnetic microscrope
  • Study the quantum communication with photonic crystals

Resume

Guozhi Chai, PhD, professor of School of physical science and technology in Lanzhou university. Born in 1984, Xingtai of Hebei province China. With the invitation of the Managing Editor of Scientific Reports, Prof. Chai now is an Editorial Board Member of Scientific Reports for Condensed matter physics. From 2012, Prof. Chai is an assessor for National Science Foundation of China. From 2011, Prof. Chai is a foreign assessor for Shota Rustaveli National Science Foundation. During his PhD study, he won “Doctoral Student Academic Award of Chinese Ministry of Education” in 2010. His research activities and interests are in Magnons-Photons interactions, Mechanism of high permeability at GHz range in thin films with rotatable anisotropy, Microwave imaging, quantum chaos in microwave devices, quantum communication with photonic crystals. Up to 21th Jan. 2016, he have published 35 papers with 15 as first author or corresponding author. 3 in Sci. Rep.(a new journal of Nature Publish Group); 3 in APL, 2 in APEX, 8 in JAP, 4 in JPD, 3 in JMMM, 5 in J. Alloy. Compd., 7 in other journals. Total citations are 298, with h index as 10 (data from web of science).

School of physics science and technology, Lanzhou University - Associate Professor

May, 2014 / Now

School of physics science and technology, Lanzhou University - Assistant Professor

Oct. 2013 / April, 2014

Temeasek Lab, Physics department, National University of Singapore - Research Scientist

Nov. 2012/ Oct. 2013

Temeasek Lab, Physics department, National University of Singapore - Associate Scientist

Feb. 2012 / Nov. 2012

School of physics science and technology, Lanzhou University - PhD on Condensed Matter Physics

Sep. 2006 / June, 2012

School of physics science and technology, Lanzhou University - Bachelor of Physics

Sep. 2002 / June, 2006

Xingtai No. 1 middle school in Hebei - Senior middle school

Sep. 1999 / June, 2002

Grants lists.


National Natural Science Foundation of China, NSFC

2019.1-2022.12 (No.51871117) (RMB 600,000)

National Natural Science Foundation of China, NSFC

2015.1-2018.12 (No. 51471080) (RMB 820,000)

National Natural Science Foundation of China, NSFC

2012.1-2014.12 (No. 51107055) (RMB 250,000)

Doctoral graduate student award in the Ministry of Education

2010.7-2011.12 (RMB 30,000)

Tianjin Dongli district government science and technology plan

2011.8-2012.7 (RMB 15,000)

Fundamental Research Funds for the Central Universities

2014.1-2015.6 (lzujbky-2014-40) (RMB 40,000)

Fundamental Research Funds for the Central Universities

2010.6-2012.5 (lzujbky-2010-219) (RMB 15,000)

The project of cultivating excellent doctoral dissertations of Lanzhou University

2011.1-2012.6

9. Chi Zhang, Yongzhang Shi, Weihua Zhang, Changjun Jiang and Guozhi Chai, Ultra-strong magnon-photon coupling induced in the photonic crystals with an YGaGeIG defect. Applied Physics Letters, 115(2): 022407, 2019.

8. Wenqiang Wang, Pingping Li, Cuimei Cao, Fufu Liu, Rujun Tang, Guozhi Chai and Changjun Jiang, Temperature dependence of interlayer exchange coupling and Gilbert damping in synthetic antiferromagnetic trilayers investigated using broadband ferromagnetic resonance. Applied Physics Letters, 113(2): 042401, 2018.

7. Dongshan Zhang, Wenjie Song and Guozhi Chai, Spin-wave magnon-polaritons in a split-ring resonator/single-crystalline YIG system. J. Phys. D: Appl. Phys. 50, 205003 (2017).

6. Chengyi Li, Guozhi Chai*, Chengcheng Yang, Wenfeng Wang and Desheng Xue. Tunable Zero-Field Ferromagnetic Resonance Frequency from S to X Band in Oblique Deposited CoFeB Thin Films. Scientific Reports, 5: 17023, 2015.

5. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong, Angular tunable zero-field ferromagnetic resonance frequency in oblique sputtered CoFeBSm thin films. Applied Physics Express 7(6): 063001-4, 2014.

4. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong. High thermal stability of zero-field ferromagnetic resonance above 5 GHz in ferrite-doped CoFe thin films. Applied Physics Letters, 103(4): 042412-5, 2013.

3. Guozhi Chai, Nguyen N. Phuoc, and C. K. Ong*, Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film. Scientific Reports. 2: 832-5, 2012.

2. Guozhi Chai, Yuancai Yang, Jingyi Zhu, Min Lin, Wenbo Sui, Dangwei Guo, Xiling Li, and Desheng Xue*. Adjust the resonance frequency of (Co90Nb10/Ta)n multilayers from 1.4 to 6.5 GHz by controlling the thickness of Ta interlayers. Applied Physics Letters, 96(1): 012505-3, 2010.

1. Guozhi Chai, Desheng Xue*, Xiaolong Fan, Xiling Li, and Dangwei Guo. Extending the Snoek’s limit of single layer film in (Co96Zr4/Cu)n multilayers. Applied Physics Letters, 93(15):152516, 2008.


Research works


In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range

In this work, we investigate the high frequency performance of Co90Zr10/SiO2/Co90Zr10 trilayers. It is demonstrated that the in-plane isotropic microwave performance is theoretically derived from the solution of the Landau-Lifshitz-Gilbert equation and experimentally achieved in that sandwich structured film. The isotropic microwave performance can be tuned to higher resonance frequency up to 5.3 GHz by employing the oblique deposition technique.

Tunable zero-field ferromagnetic resonance frequency from S to X band in oblique deposited CoFeB thin films

We performed an investigation of the static and high frequency magnetic properties for oblique sputtered CoFeB thin films. The static magnetic results revealed that oblique sputtered CoFeB thin films possess well defined in-plane uniaxial magnetic anisotropy, which increases monotonically from 50.1 to 608.8 Oe with the increasing of deposition angle from 10° to 70°. Continuous modification of the resonance frequency of CoFeB thin films in a range of 2.83–9.71 GHz (covers three microwave bands including S, C and X bands) has been achieved.

Spin wave magnon-polaritons in a split-ring resonator/single crystalline YIG system

In this work, the spin wave magnon-polaritons are studied by using a split-ring resonator loaded by a round shape single-crystal bulk yttrium-iron-garnet chip. The coherent magnon-photon coupling of high index modes spin-wave resonances as well as ferromagnetic resonance with SRR resonances can be observed. The coupling strength is mode dependent and it decreases with increasing mode index. These results may be useful for understanding the strongly hybridized spin wave magnonphoton coupling system.

A designed shorted microstrip probe for detecting the temperature dependence high frequency permeability of magnetic thin films

A temperature dependence characterization system of microwave permeability of magnetic thin film up to 10 GHz in the temperature range from room temperature up to 200 °C is designed and fabricated. It is based on a designed one-port shorted microstrip probe made by microwave printed circuit board (PCB) for detecting the high frequency permeability of magnetic thin films without limitations in sample size. Without contacting the magnetic thin films to the probe, the microwave permeability of the film can be detected with almost as the same accuracy by comparing with the shorted microstrip transmission-line fixture. The complex permeability can be deduced by an analytical approach from the measured reflection coefficient of a strip line (S11) with and without a ferromagnetic film material on it. The procedures are the same with the shorted microstrip transmission-line method. The microwave permeability of an oblique deposited CoZr thin film was investigated with this probe. The room temperature permeability results of the CoZr film agree well with results obtained from the established short-circuited microstrip perturbation method. Temperature dependence permeability results fit well with the Landau–Lifshitz–Gilbert equation. Developments of the temperature dependent measurement of magnetic properties of the magnetic thin film are important to the high frequency applications of magnetic devices at high temperatures.

principle of Brillouin light scattering (BLS)

Publications

Up to 21th May. 2018, I have published 39 papers with 20 as first author or corresponding author. 3 in APL, 2 in APEX, 8 in JAP, 6 in JPD, 4 in Sci. Rep., 3 in JMMM, 5 in J. Alloy. Compd., 8 in other journals. Total citations are 459, with h index as 13 (data from web of science).

Selected Publications

9. Chi Zhang, Yongzhang Shi, Weihua Zhang, Changjun Jiang and Guozhi Chai, Ultra-strong magnon-photon coupling induced in the photonic crystals with an YGaGeIG defect. Applied Physics Letters, 115(2): 022407, 2019.

8. Wenqiang Wang, Pingping Li, Cuimei Cao, Fufu Liu, Rujun Tang, Guozhi Chai and Changjun Jiang, Temperature dependence of interlayer exchange coupling and Gilbert damping in synthetic antiferromagnetic trilayers investigated using broadband ferromagnetic resonance. Applied Physics Letters, 113(2): 042401, 2018.

7. Dongshan Zhang, Wenjie Song and Guozhi Chai, Spin-wave magnon-polaritons in a split-ring resonator/single-crystalline YIG system. J. Phys. D: Appl. Phys. 50, 205003 (2017).

6. Chengyi Li, Guozhi Chai*, Chengcheng Yang, Wenfeng Wang and Desheng Xue. Tunable Zero-Field Ferromagnetic Resonance Frequency from S to X Band in Oblique Deposited CoFeB Thin Films. Scientific Reports, 5: 17023, 2015.

5. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong, Angular tunable zero-field ferromagnetic resonance frequency in oblique sputtered CoFeBSm thin films. Applied Physics Express 7(6): 063001-4, 2014.

4. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong. High thermal stability of zero-field ferromagnetic resonance above 5 GHz in ferrite-doped CoFe thin films. Applied Physics Letters, 103(4): 042412-5, 2013.

3. Guozhi Chai, Nguyen N. Phuoc, and C. K. Ong*, Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film. Scientific Reports. 2: 832-5, 2012.

2. Guozhi Chai, Yuancai Yang, Jingyi Zhu, Min Lin, Wenbo Sui, Dangwei Guo, Xiling Li, and Desheng Xue*. Adjust the resonance frequency of (Co90Nb10/Ta)n multilayers from 1.4 to 6.5 GHz by controlling the thickness of Ta interlayers. Applied Physics Letters, 96(1): 012505-3, 2010.

1. Guozhi Chai, Desheng Xue*, Xiaolong Fan, Xiling Li, and Dangwei Guo. Extending the Snoek’s limit of single layer film in (Co96Zr4/Cu)n multilayers. Applied Physics Letters, 93(15):152516, 2008.

2019

1. Lulu Pan; Wenfeng Wang; Wentao Wang; Peng Zhang; Li Xi; Guozhi Chai; Desheng Xue, Rotatable anisotropy in Fe4N thin film with quasi-single magnetic domain.Journal of Alloys and Compounds.777, 1191-1196 (2019).

2.Cuimei Cao, Lvkang Shen, Shiwei Chen, Kunya Yang, Guohua Lan, Pingping Li, Wenqiang Wang, Ming Liu, Guozhi Chai and Changjun Jiang, Reciprocal-space-resolved piezoelectric control of non-volatile magnetism in epitaxial LiFe5O8 film on Pb(Mg1/3Nb2/3)0.7Ti0.3O3 substrate. Applied Physics Letters, 114: 112402, 2019.

3. Chi Zhang, Yongzhang Shi, Weihua Zhang, Changjun Jiang and Guozhi Chai, Ultra-strong magnon-photon coupling induced in the photonic crystals with an YGaGeIG defect. Applied Physics Letters, 115(2): 022407, 2019.

4. Yongzhang Shi; Dongshan Zhang; Changjun Jiang; Guozhi Chai, Control of photon-magnon coupling with a nonuniform microwave magnetic field. J. Phys. D: Appl. Phys. 52: 305003, 2019.

5. Yangping Wang, Fufu Liu, Cuimei Cao, Cai Zhou, Guozhi Chai, and Changjun Jiang, Ionic-liquid gating controls anomalous hall resistivity of Co/Pt perpendicular magnetic anisotropy films. Journal of Magnetism and Magnetic Materials, 491, 165626, 2019.

2018

1. Huige Ma, Chengyi Li, Wenfeng Wang and Guozhi Chai1, Thickness-dependent resonance frequency of non-uniform procession mode in CoZr stripe-domain magnetic films. J. Phys. D: Appl. Phys. 51, 285004 (2018).

2. Wenqiang Wang, Pingping Li, Cuimei Cao, Fufu Liu, Rujun Tang, Guozhi Chai, and Changjun Jiang, Temperature dependence of interlayer exchange coupling and Gilbert damping in synthetic antiferromagnetic trilayers investigated using broadband ferromagnetic resonance. Applied Physics Letters. 113, 042401 (2018).

3. Cunxu,Gao ; Yu,Miao ;Yutian,Wang ; Guozhi ,Chai,;Peng,Chen, ; Desheng,Xue, Interface-induced spiral magnetic structure of epitaxial Fe films on GaAs(001). Aip Advances. 8, 125026 (2018).

2016

1. Lulu Pan, Fenglong Wang, Wenfeng Wang, Guozhi Chai* and Desheng Xue*. In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range. Scientific Reports, 6: 21327, 2016.

2015

1. Zhiling Wang, Xiaolong Fan*, Xiaobing Zhao, Guozhi Chai, Desheng Xue, Fabrication of Co90Zr10 thin films with adjustable resonance frequency from 1.8 to 7.1 GHz. Journal of Alloys and Compounds, 628: 236-239, 2015.

2. Cunxu Gao, Yutian Wang*, Chengyi Li, Yanping Wei, Zhendong Chen, Guozhi Chai and Desheng Xue, Multidirectional available high-frequency response with zero-field resonance above 8 GHz in epitaxial α-Fe(001) films. Applied Physics Express 8(5): 053001-3, 2014.

3. Guozhi Chai*, Xinhua Wang, Zhiling Wang and Desheng Xue, Tunable microwave magnetic properties in oblique deposited CoHf/Ta multilayers. Journal of Applied Physics, 117(6): 063901-5, 2015.

4. X. D. Jiang, D. W. Guo, C. H. Zhang, X. L. Fan, G. Z. Chai and D. S. Xue*. Influence of the Interface on the Magnetic Properties of Nizn Ferrite Thin Films Treated by Proton Irradiation. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 358: 1-5, 2015.

5. Chengyi Li, Guozhi Chai*, Chengcheng Yang, Wenfeng Wang and Desheng Xue. Tunable Zero-Field Ferromagnetic Resonance Frequency from S to X Band in Oblique Deposited CoFeB Thin Films. Scientific Reports, 5: 17023, 2015.

2014

1. Xiaoxi Zhong*, Nguyen N. Phuoc, Guozhi Chai, Ying Liu, C.K. Ong, Thermal stability and dynamic magnetic properties of FeSiAl films fabricated by oblique deposition. Journal of Alloys and Compounds, 610: 126-131, 2014.

2. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong, Angular tunable zero-field ferromagnetic resonance frequency in oblique sputtered CoFeBSm thin films. Applied Physics Express 7(6): 063001-4, 2014.

3. Xinhua Wang, Guozhi Chai*, and Desheng Xue*, Magnetic properties of (Co92Zr8/SiO2)15 multilayer thin films for GHz applications. Journal of Alloys and Compounds, 584: 171-174, 2014.

4. Wee Tee Soh, Bin Peng, Guozhi Chai, and C. K. Ong*, Note: Electrical detection and quantification of spin rectification effect enabled by shorted microstrip transmission line technique. Review of Scientific Instruments, 85: 026109-3, 2014.

2013

1. Guozhi Chai*, Xinhua Wang, M. S. Si, Desheng Xue, Adjustable microwave permeability of nanorings: A micromagnetic investigation. Physics Letters A, 377(21-22): 1491-1494, 2013.

2. Nguyen N. Phuoc*, Wee Tee Soh, Guozhi Chai, and C. K. Ong, Investigation of magnetic properties and microwave characteristics of obliquely sputtered NiFe/MnIr bilayers. Journal of Applied Physics, 113(7): 073902-6, 2013.

3. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong. High thermal stability of zero-field ferromagnetic resonance above 5 GHz in ferrite-doped CoFe thin films. Applied Physics Letters, 103(4): 042412-5, 2013.

4. Gaoxue Wang, Chunhui Dong, Zhongjie Yan, Tao Wang, Guozhi Chai, Changjun Jiang*, and Desheng Xue. Controlling of magnetic domain structure by sputtering films on tilted substrates. Journal of Alloys and Compounds, 573: 118-121, 2013.

5. Guozhi Chai*, Nguyen N. Phuoc, and C. K. Ong. Optimizing high-frequency properties of stripe domain ferrite doped CoFe thin films by means of a Ta buffer layer. Journal of Physics D: Applied Physics 46(4): 415001-7, 2013.

2012

1. Guozhi Chai, Nguyen N. Phuoc, and C. K. Ong*, Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film. Scientific Reports. 2: 832-5, 2012.

2. Nguyen N. Phuoc*, Guozhi Chai, and C. K. Ong, Temperature-dependent dynamic magnetization of FeCoHf thin films fabricated by oblique deposition. Journal of Applied Physics, 112(8): 083925-6, 2012.

3. Nguyen N. Phuoc*, Guozhi Chai, and C. K. Ong, Enhancing exchange bias and tailoring microwave properties of FeCo/MnIr multilayers by oblique deposition. Journal of Applied Physics, 112(11): 113908-6, 2012.

4. Gaoxue Wang, Chunhui Dong, Changjun Jiang*, Guozhi Chai, Desheng Xue, Effect of nanoparticle size on magnetic damping parameter in Co92Zr8 soft magnetic films. Journal of Magnetism and Magnetic Materials, 324(18): 2840-2803, 2012.

5. Gaoxue Wang, Chunhui Dong, Wenxi Wang, Zhiling Wang, Guozhi Chai, Changjun Jiang*, and Desheng Xue, Observation of rotatable stripe domain in permalloy films with oblique sputtering. Journal of Applied Physics, 112(9): 093907-4, 2012.

6. Xu Yan, Daqiang Gao, Guozhi Chai, Desheng Xue*, Adjustable microwave absorption properties of flake shaped (Ni0.5Zn0.5)Fe2O4/Co nanocomposites with stress induced orientation. Journal of Magnetism and Magnetic Materials, 324(11):1902-1906, (2012).

2011

1. Xu Yan, Guozhi Chai, and Desheng Xue*, The improvement of microwave properties for Co flakes after silica coating. Journal of Alloys and Compounds, 509(4): 1310-1313, 2011.

2. Wenbo Sui, Jingyi Zhu, Jinyun Li, Guozhi Chai, Changjun Jiang, Xiaolong Fan, and Desheng Xue*, Determination of the anisotropies and reversal process in exchange-bias bilayers using a rotational magnetization curve approach. Journal of Applied Physics, 109(10): 103902-6, 2011.

3. Guozhi Chai, Dangwei Guo, Xiaolong Fan and Desheng Xue*, Microwave magnetic properties of soft magnetic thin films. Science China Physics, Mechanics & Astronomy. 54(7): 1200-1207, 2011

4. Guozhi Chai, Zhiling Wang, Gaoxue Wang, Wenbo Sui, and Desheng Xue*, Adjustable Microwave Properties in FeCoZr/Cu Multilayers. IEEE Transactions on Magnetics. 47(10): 3115-3117, 2011.

2010

1. Guozhi Chai, Nguyen N. Phuoc, and C. K. Ong*, Exchange coupling driven omnidirectional rotatable anisotropy in ferrite doped CoFe thin film. Scientific Reports. 2: 832-5, 2012.

2. Dangwei Guo, Xiaolong Fan, Guozhi Chai, Changjun Jiang, Xiling Li, and Desheng Xue*. Structural and magnetic properties of NiZn ferrite films with high saturation magnetization deposited by magnetron sputtering. Applied Surface Science, 256(8): 2319-2322, 2010.

3. Dangwei Guo, Jingyi Zhu, Yuancai Yang, Xiaolong Fan, Guozhi Chai, Wenbo Sui, Zhengmei Zhang, and Desheng Xue*. High-frequency magnetic properties of Zn ferrite films deposited by magnetron sputtering. Journal of Applied Physics, 107(4): 043903, 2010.

4. Zhengmei Zhang, Min Lin, Jingyi Zhu, Dangwei Guo, Guozhi Chai, Xiaolong Fan*, Yuancai Yang, and Desheng Xue*. Effect of light rare earth element Nd doping on magnetization dynamics in Co-Nb films. Journal of Applied Physics, 107(8): 083912, 2010.

5. Zhengmei Zhang, Xiaolong Fan*, Min Lin, Dangwei Guo, Guozhi Chai, and Desheng Xue*. Optimized soft magnetic properties and high frequency characteristics of obliquely deposited Co-Zr thin films. Journal of Physics D: Applied Physics, 43(8): 085002, 2010.

2009

1. Guozhi Chai, Dangwei Guo, Xiling Li, Jingyi Zhu, Wenbo Sui, and Desheng Xue*. Magnetic properties of (Co0.65Fe0.35 )1-x(Ni0.5 Zn0.5 Fe2 O4 )x bi-magnetic composite granular films for high frequency application. Journal of Physics D: Applied Physics, 42(20):205006, 2009.

2. Xi-Ling Li, Guo-Zhi Chai, Dang-Wei Guo, Bo Gao, Zheng-Mei Zhang, and De-Sheng Xue*. Increasing the thin film inductance by using soft magnetic Co92Zr8 as conductor. Microelectronic Engineering, 86(11):2290, 2009.

3. Dangwei Guo, Zhengmei Zhang, Min Lin, Xiaolong Fan, Guozhi Chai, Yan Xu, and Desheng Xue*. Ni-Zn ferrite films with high resonance frequency in the gigahertz range deposited by magnetron sputtering at room temperature. Journal of Physics D: Applied Physics, 42(12):125006, 2009.

2008

1. Guozhi Chai, Desheng Xue*, Xiaolong Fan, Xiling Li, and Dangwei Guo. Extending the Snoek’s limit of single layer film in (Co96Zr4/Cu)n multilayers. Applied Physics Letters, 93(15):152516, 2008.

2. Desheng Xue, Guozhi Chai*, Xiling Li, and Xiaolong Fan, Effects of grain size distribution on coercivity and permeability of ferromagnets. Journal of Magnetism and Magnetic Materials, 320(8):1541, (2008).

Team members

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Events

Open positions

2-3graduated students per year, Please contact Prof. Chai fro details.
1-2 PhD students per year, Please contact Prof. Chai fro details.

Collaborations

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