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Publications (10 of 180) Show all publications
Mottamchetty, V., Rani, P., Brucas, R., Rydberg, A., Svedlindh, P. & Gupta, R. (2023). Direct evidence of terahertz emission arising from anomalous Hall effect. Scientific Reports, 13(1), Article ID 5988.
Open this publication in new window or tab >>Direct evidence of terahertz emission arising from anomalous Hall effect
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2023 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 13, no 1, article id 5988Article in journal (Refereed) Published
Abstract [en]

A detailed understanding of the different mechanisms being responsible for terahertz (THz) emission in ferromagnetic (FM) materials will aid in designing efficient THz emitters. In this report, we present direct evidence of THz emission from single layer Co0.4Fe0.4B0.2 (CoFeB) FM thin films. The dominant mechanism being responsible for the THz emission is the anomalous Hall effect (AHE), which is an effect of a net backflow current in the FM layer created by the spin polarized current reflected at the interfaces of the FM layer. The THz emission from the AHE-based CoFeB emitter is optimized by varying its thickness, orientation, and pump fluence of the laser beam. Results from electrical transport measurements show that skew scattering of charge carriers is responsible for the THz emission in the CoFeB AHE-based THz emitter.

Place, publisher, year, edition, pages
Springer Nature, 2023
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-509239 (URN)10.1038/s41598-023-33143-w (DOI)001034742000077 ()37045934 (PubMedID)
Funder
Swedish Research Council, 2021-04658Swedish Research Council, 2018-04918Swedish Research Council, 201703725
Available from: 2023-08-21 Created: 2023-08-21 Last updated: 2023-08-21Bibliographically approved
Ruber, R., Bhattacharyya, A., Dancila, D., Ekelöf, T., Eriksson, J., Fransson, K., . . . Ziemann, V. (2021). Accelerator development at the FREIA Laboratory. Journal of Instrumentation, 16(7)
Open this publication in new window or tab >>Accelerator development at the FREIA Laboratory
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2021 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 16, no 7Article in journal (Refereed) Published
Abstract [en]

The FREIA Laboratory at Uppsala University focuses on superconducting technology and accelerator development. It actively supports the development of the European Spallation Source, CERN, and MAX IV, among others. FREIA has developed test facilities for superconducting accelerator technology such as a double-cavity horizontal test cryostat, a vertical cryostat with a novel magnetic field compensation scheme, and a test stand for short cryomodules. Accelerating cavities have been tested in the horizontal cryostat, crab-cavities cavities in the vertical cryostat, and cryomodules for ESS on the cryomodule test stand. High power radio-frequency amplifier prototypes based on vacuum tube technology were developed for driving spoke cavities. Solid-state amplifiers and power combiners are under development for future projects. We present the status of the FREIA Laboratory complemented with results of recent projects and future prospects.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP)IOP PUBLISHING LTD, 2021
Keywords
Acceleration cavities and superconducting magnets (high-temperature superconduc- tor, radiation hardened magnets, normal-conducting, permanent magnet devices, wigglers and undulators), Accelerator Subsystems and Technologies
National Category
Accelerator Physics and Instrumentation
Identifiers
urn:nbn:se:uu:diva-456486 (URN)10.1088/1748-0221/16/07/P07039 (DOI)000694909000015 ()
Funder
Knut and Alice Wallenberg FoundationEU, Horizon 2020, 730871EU, Horizon 2020, 777419EU, Horizon 2020, 777431
Available from: 2021-10-19 Created: 2021-10-19 Last updated: 2024-01-15Bibliographically approved
Gupta, R., Husain, S., Kumar, A., Brucas, R., Rydberg, A. & Svedlindh, P. (2021). Co2FeAl Full Heusler Compound Based Spintronic Terahertz Emitter. Advanced Optical Materials, 9(10), Article ID 2001987.
Open this publication in new window or tab >>Co2FeAl Full Heusler Compound Based Spintronic Terahertz Emitter
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2021 (English)In: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, Vol. 9, no 10, article id 2001987Article in journal (Refereed) Published
Abstract [en]

To achieve a large terahertz (THz) amplitude from a spintronic THz emitter (STE), materials with 100% spin polarisation such as Co-based Heusler compounds as ferromagnetic layer are required. However, these compounds are known to loose their half-metallicity in the ultrathin film regime, as it is difficult to achieve L2(1) ordering, which has become a bottleneck for the film growth. Here, the successful deposition using room temperature DC sputtering of the L2(1) and B2 ordered phases of the Co2FeAl full Heusler compound is reported. Co2FeAl is used as ferromagnetic layer together with highly orientated Pt as nonferromagnetic layer in the Co2FeAl/Pt STE, where an MgO (10 nm) seed layer plays an important role to achieve the L2(1) and B2 ordering of Co2FeAl. The THz generation in the Co2FeAl/Pt STE is presented, which has a bandwidth of 0.2-4 THz. The THz electric field amplitude is optimized with respect to thickness, orientation, and growth parameters using a thickness dependent model considering the optically induced spin current, superdiffusive spin current, inverse spin Hall effect, and the THz attenuation in the layers. This study, based on the full Heusler Co2FeAl compound opens up a plethora of possibilities in STE research involving full Heusler compounds.

Place, publisher, year, edition, pages
John Wiley & SonsWiley, 2021
Keywords
B2 ordering, Co2FeAl, full Heusler compound, L2(1) ordering, spintronic THz emitter, sputtering, terahertz time&#8208, domain spectroscopy, THz attenuation coefficient
National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-446626 (URN)10.1002/adom.202001987 (DOI)000625973700001 ()
Funder
Swedish Research Council, 2017-03799
Available from: 2021-06-22 Created: 2021-06-22 Last updated: 2024-01-15Bibliographically approved
Gupta, R., Bagherikorani, E., Mottamchetty, V., Dancila, D., Brucas, R., Rydberg, A. & Svedlindh, P. (2021). Substrate Effect on Terahertz Emission in Fe/Pt Spintronic Emitters. In: 2021 46th International Conference On Infrared, Millimeter And Terahertz Waves (IRMMW-THZ): . Paper presented at 46th International Conference on Infrared and Millimeter Waves, Online, AUG 30-SEP 03, 2021. Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Substrate Effect on Terahertz Emission in Fe/Pt Spintronic Emitters
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2021 (English)In: 2021 46th International Conference On Infrared, Millimeter And Terahertz Waves (IRMMW-THZ), Institute of Electrical and Electronics Engineers (IEEE), 2021Conference paper, Published paper (Other academic)
Abstract [en]

The choice of the substrate plays an important role for spintronic terahertz (THz) emitters (STEs). We have grown epitaxial Pt/Fe bilayer thin films on MgO and MgAl2O4 substrates. The THz electric field amplitude is found to be larger when Pt/Feis is grown on MgO even though the crystal quality of the Fe film is better when grown on MgAl2O4. This study indicates that the Fecrystal quality affects the THz emission in Pt/Fe STEs and points to the importance of a careful choice of the substrate to enhance the THz amplitude in STEs.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2021
Series
International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz), ISSN 2162-2027
Keywords
Crystals, Iron, Epitaxial growth, Electric fields, Substrate, Spintronics
National Category
Condensed Matter Physics
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-457008 (URN)10.1109/IRMMW-THz50926.2021.9567421 (DOI)000782468300542 ()978-1-7281-9424-0 (ISBN)
Conference
46th International Conference on Infrared and Millimeter Waves, Online, AUG 30-SEP 03, 2021
Funder
Olle Engkvists stiftelse, 182-0365Swedish Research Council, 2017-03799
Available from: 2021-10-26 Created: 2021-10-26 Last updated: 2022-06-02Bibliographically approved
Aziz, I., Dahlback, R., Öjefors, E., Sjogren, K., Rydberg, A. & Dancila, D. (2019). 60 GHz compact broadband antenna arrays with wide-angle beam steering. The Journal of Engineering (8), 5407-5414
Open this publication in new window or tab >>60 GHz compact broadband antenna arrays with wide-angle beam steering
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2019 (English)In: The Journal of Engineering, ISSN 1872-3284, E-ISSN 2051-3305, no 8, p. 5407-5414Article in journal (Refereed) Published
Abstract [en]

Highly integrated multilayered printed circuit board-based patch antenna arrays are proposed in this study for 60 GHz wireless communications. Electromagnetic coupling between two stacked patches is used to achieve the broadband performance. Different structures of single element antennas, two-element antenna arrays and four-element antenna arrays are presented. The two compact four-element antenna arrays show < -10 dB impedance bandwidth of 13 and 14.6% with 12 dBi peak gain. The arrays have the 3 dB gain bandwidth of 9 and 13%. A single column, four-element sub-array is used to design 4 x 16 antenna array. This array delivers 20.8 dBi peak gain with 13% impedance and gain bandwidth. Furthermore, a two-element series fed array is used to realise a 2 x 16 phased antenna array. This array is fed through a 16 x channel radio frequency IC to achieve the beam steering in +/- 50 degrees range.

Place, publisher, year, edition, pages
INST ENGINEERING TECHNOLOGY-IET, 2019
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-393830 (URN)10.1049/joe.2018.5343 (DOI)000482435600007 ()
Available from: 2019-10-01 Created: 2019-10-01 Last updated: 2021-01-26Bibliographically approved
Aziz, I., Öjefors, E., Dahlbäck, R., Rydberg, A., Engblom, G. & Dancila, D. (2019). Broadband Connected Slots Phased Array Feeding a High Gain Lens Antenna at 60 GHz. In: 2019 49th European Microwave Conference (EuMC): . Paper presented at 49th European Microwave Conference, Paris, France, 1-3 October, 2019. (pp. 718-721).
Open this publication in new window or tab >>Broadband Connected Slots Phased Array Feeding a High Gain Lens Antenna at 60 GHz
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2019 (English)In: 2019 49th European Microwave Conference (EuMC), 2019, p. 718-721Conference paper, Published paper (Refereed)
National Category
Telecommunications
Identifiers
urn:nbn:se:uu:diva-400789 (URN)10.23919/EuMC.2019.8910856 (DOI)000520507700174 ()978-2-87487-055-2 (ISBN)
Conference
49th European Microwave Conference, Paris, France, 1-3 October, 2019.
Funder
Vinnova, 2016-01800
Available from: 2020-01-03 Created: 2020-01-03 Last updated: 2020-04-23Bibliographically approved
Dancila, D., Beuerle, B., Shah, U., Oberhammer, J. & Rydberg, A. (2019). Leaky Wave Antenna at 300 GHz in Silicon Micromachined Waveguide Technology. In: 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz): . Paper presented at 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), SEP 01-06, 2019, Paris, FRANCE.
Open this publication in new window or tab >>Leaky Wave Antenna at 300 GHz in Silicon Micromachined Waveguide Technology
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2019 (English)In: 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2019Conference paper, Published paper (Refereed)
Abstract [en]

A leaky wave antenna composed of eight slots in a gold metallised silicon micromachined waveguide was designed, fabricated and measured at 300 GHz. The measured results are in good agreement with the simulations.

Series
International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), ISSN 2162-2027, E-ISSN 2162-2035
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:uu:diva-438570 (URN)10.1109/IRMMW-THz.2019.8873927 (DOI)000591783800236 ()978-1-5386-8285-2 (ISBN)978-1-5386-8286-9 (ISBN)
Conference
44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), SEP 01-06, 2019, Paris, FRANCE
Funder
Swedish Foundation for Strategic Research , SE13-007
Available from: 2021-03-25 Created: 2021-03-25 Last updated: 2021-03-25Bibliographically approved
Holmberg, M., Dancila, D., Rydberg, A., Hjörvarsson, B., Jansson, U., Marattukalam, J. J., . . . Andersson, J. (2018). Direct metal laser sintering printed millimeter and submillimeter waveguides. In: : . Paper presented at GigaHertz Symposium, Lund, May 24-25 2018.
Open this publication in new window or tab >>Direct metal laser sintering printed millimeter and submillimeter waveguides
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2018 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Telecommunications
Identifiers
urn:nbn:se:uu:diva-369172 (URN)
Conference
GigaHertz Symposium, Lund, May 24-25 2018
Funder
Swedish Foundation for Strategic Research , GMT14-0048
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Aziz, I., Rydberg, A. & Dancila, D. (2018). Electromagnetically Coupled Multilayer Patch Antenna for 60 GHz Communications. In: : . Paper presented at GigaHertz Symposium, Lund, May 24-25, 2018..
Open this publication in new window or tab >>Electromagnetically Coupled Multilayer Patch Antenna for 60 GHz Communications
2018 (English)Conference paper, Oral presentation only (Refereed)
National Category
Telecommunications
Identifiers
urn:nbn:se:uu:diva-369169 (URN)
Conference
GigaHertz Symposium, Lund, May 24-25, 2018.
Funder
VINNOVA, 2016-01800
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2019-01-17Bibliographically approved
Aziz, I., Dahlbäck, R., Öjefors, E., Rydberg, A. & Dancila, D. (2018). High Gain Compact 57-66 GHz Antenna Array for Backhaul & Access Communications. In: 12th European Conference on Antennas and Propagation (EuCAP 2018): . Paper presented at 12th European Conference on Antennas and Propagation (EuCAP 2018), 9-13 April, London.
Open this publication in new window or tab >>High Gain Compact 57-66 GHz Antenna Array for Backhaul & Access Communications
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2018 (English)In: 12th European Conference on Antennas and Propagation (EuCAP 2018), 2018Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Highly integrated multilayered patch antenna arrays are proposed in this paper for 60 GHz wireless communications. Electromagnetic coupling between two stacked patches is used for improving the broadband performance. Three different structures of single column 4-element arrays are presented with center and corporate feeding networks. Maximum gain of 12.2 dBi and <-10 dB return loss in the entire unlicensed frequency band 57-66 GHz is measured. Furthermore, a compact 4×16 antenna array (41 mm x 13 mm) is presented with 18.7 dBi maximum gain, 8 GHz (5765) bandwidth and 7° HPBW (half power beam width) in H plane.

Keywords
planar antenna arrays, directive antennas, microstrip antenna arrays, broadband antennas, millimetre wave antenna arrays, antenna radiation patterns, electromagnetic coupling, antenna feeds
National Category
Telecommunications
Identifiers
urn:nbn:se:uu:diva-428186 (URN)10.1049/cp.2018.0362 (DOI)978-1-78561-816-1 (ISBN)
Conference
12th European Conference on Antennas and Propagation (EuCAP 2018), 9-13 April, London
Available from: 2020-12-12 Created: 2020-12-12 Last updated: 2021-01-28Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2401-2981

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