Research Interests

Superconducting nanostructures
Josephson junctions, SQUIDs, applications in quantum communications and metrology.
Mesoscale and Nanoscale Physics
Electronic transport in 2DEG, graphene and van der Waals heterostructures, quantum Hall effect.
Low temperature physics
Superconductivity, superfluidity, cryogenics using ³He sorption pump refrigerator and ³He/⁴He dilution refrigarators.

Main skills

  • Cryogenics, dilution and sportion pumped refrigerators, magnetoresistance measurements
  • Lock-in measurements, signal processing & filtering
  • Nanofabrication, graphene & 2D materials, van der Waals heterostructures
  • Electron microscopy, synchrotron X-ray techniques, X-ray diffraction, X-ray photoemission spectroscopy, IR spectroscopy

Professional appointments

EPSRC Doctoral Prize Fellow Manchester, UK. 2022-2023
  • School of Physics and Astronomy, The University of Manchester
Graduate Teaching Assistant Manchester, UK. 2018-2021
  • School of Physics and Astronomy, The University of Manchester
Visiting student Researcher Menlo Park, CA, USA. 2018.
  • SLAC National Accelerator Laboratory,
  • supervisor: Prof Prof. Michael F Toney.
R&D Intern Lyon + Chambéry, France. 2017
  • Synthesised + characterised nanocharged acrylic adhesives for the encapsulation of optoelectronic devices.
  • Enhanced the barrier properties towads gases and water with proper dispersion of nanocharges.
  • Carried out compatibility tests of the produced adhesives to Organic and Perovskite Solar Cells.
  • Synthesised solgel zirconium phosphate nanoplatelets, and functionnalised their surfaces.
  • Collaboration project between Arkema, CEA and ENS Lyon
  • Supervisors: Dr Stéphane Cros (CEA), Dr Frédéric Chaput (ENS) and Dr Manuel Hidalgo (Arkema) Test preparation instructor Paris, France, 2016-2017
    • French ministry of higher education

Education

Ph.D. in Condensed Matter Physics Manchester, UK. grad. 2022
  • School of Physics and Astronomy, The University of Manchester
  • Thesis: Electronic properties of graphene heterostructures below 1K
  • Supervisor: Pr Andre K. Geim;
  • oral exampination: 12 September 2022
M.Sc. in Chemical Physics Paris, France. grad. 2018
  • ESPCI Paris: École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris
  • Diplôme d'ingénieur (engineering degree)
B.Sc. in Physics Paris, France. grad. 2016
  • Sorbonne Université - Université Pierre-et-Marie-Curie

Prizes and Awards

  1. Seal of excellence February 2023
    Marie Skłodowska-Curie Actions (total scole 99.4%)
  2. Graphene Week student grant September 2022
    EU Graphene Flagship
    €300
  3. CR Barber Trust Travel grant June 2022
    Institute of Physics
    £100
  4. Distinguished Student Award March 2022
    Forum for International Physics, American Physical Society
    $500
    International award to 9 outstanding graduate students
  5. Doctoral Prize February 2022
    EPSRC + The University of Manchester
    top 5% EPSRC-funded PhD students at The University of Manchester
  6. Best Student Talk October 2020
    Graphene conference (Grenoble, France)
    €200
    international conference, 1 laureate among ~50 talks
  7. Graphene conference travel grant June 2020
    Graphene conference
    (cancelled because of covid-19)
    international conference, awarded to top 10% based on abstract proposal
  8. Engineer of the future for Research December 2019
    (Ingénieur du futur dans la catégorie Recherche)
    L’Usine Nouvelle, UTC & Sorbonne Université
    €2,500
    national award, candidates nominated by French higher education institution, 1 laureate
  9. Graphene Week student grant September 2019
    EU Graphene Flagship
    €300
  10. Finalist for Distinguished Student Prize May 2018
    ESPCI Alumni
    top 5 students in a cohort of 100
  11. Excellence Scholarship for Visiting Student Researcher at SLAC June 2022
    Fonds ESPCI Paris
    €3,00
    top 10 students in a cohort of 100

Research funding

  1. EPSRC Doctoral Prize Fellowship July 2022 - 1 year
    £51,320
    EPSRC, UKRI #EP/T5117823/1
  2. Doctoral Training Partnership Bursary September 2018 - 4 years
    ~£80,000 (including tuition)
    EPSRC, UKRI #2109254

Teaching

Tutor Manchester, UK. 2020-2021
  • Department of Physics & Astronomy, School of Natural Sciences, The University of Manchester
  • 2nd-year Tutorials in Quantum Mechanics, Electromagnetism and waves
  • Provide student pastoral support per group of 5
  • Marking of assignments
  • 2 hours per week
Graduate Teaching Assistant Manchester, UK. 2018-2019
& 2019-2020 & 2020-2021
& 2021
  • Department of Physics & Astronomy, School of Natural Sciences, The University of Manchester.
  • Introduction to Programming for Physicists:
  • 2nd year undergraduate (Python & C++ in 2018-2019, Python & numerical methods in 2019-2020)
  • Assessed and advised students
  • Marking of assignments
  • 7 hours per week
  • Condensed Matter Physics labs:
  • 3rd year undergraduate (AFM, STM, NMR, Spin Echo, Hall effect, Schockley-Haynes experiment, graphene characterisation, particle detector, 2020-2021 and 2021-2022 S1)
  • Assessed and advised students
  • 7 hours per week
  • Physics project
  • Foundation year, diiffraction experiments
  • Participation in devising the curriculum
  • Demonstrated, assessed and advised students
  • Marked the exam papers
  • Marked the oral presentations
  • 6h per week
Test preparation instructor Paris, France. 2016-2017
  • Mathematics (Algebra & Analysis)
  • Lycée Saint Louis, 1st year undergraduate
  • Prepared students attending “Classes Préparatoires aux Grandes Écoles” for the Mathematics oral exam to the French Grandes Écoles for scientific studies.
  • Provided pastoral support per group of 3
  • Assessed
  • 2 hours per week

Leadership and activities

Cohort Representative 2018-.
  • ESPCI Alumni Association
  • Organisation of the graduation ceremony and party.
  • Census of the graduates.
  • Organise cohort meetups (ski weekend, weekend in Normandy, etc.)
  • Relay ESPCI Alumni Association's mutual aid in the class of 2018.
  • Promote ESPCI Alumni's events.
Communications and Public Relations Officer 2016.
  • ESPCI Student's Sport Union
  • Set up communications and growth strategy.
  • Designed visual identity.
  • Mapped out, promoted and implemented the communications framework & platforms strategy.
  • Managed digital communications channels.
  • Designed and fundraised for the sport jerseys.
  • Negociated sponsorships.
  • Managed public & press relations.
  • Results: ×3 growth in membership, ×4 growth in sponsorship revenues.
Communications Officer 2009-2012.
  • Jappix, web-based communication platform
  • Co-founded the open-source program.
  • Managed UI design.
  • Developped a communications and marketing strategy.
  • Results: 100k+ downloads, 50k+ users on jappix.com.
Event organisation
  • ESPCI Gala Dinner, 2018, Communications Officer.
  • ESPCI Gala Dinner, 2016, Vice President.
  • Journée de l'Informatique Libre (Free Software Day) 2011, Conference Program committee officer.

Publications

Preprints, currently under review
  1. N. Xin, J. Lourembam, P. Kumaravadivel, A. E. Kazantsev, Z. Wu, C. Mullan, J. Barrier, A. A. Geim, I. V. Grigorieva, A. Mishchenko, A. Principi, V. I. Fal’ko, L. A. Ponomarenko, A. K. Geim, and A. I. Berdyugin, Giant Magnetoresistance of Dirac Plasma in High-Mobility Graphene, (2023). [arXiv:2302.06863] [DOI] 
    @unpublished{xin2023nature,
  author = {Xin, Na and Lourembam, James and Kumaravadivel, Piran and Kazantsev, Alexander E and Wu, Zefei and Mullan, Ciaran and Barrier, Julien and Geim, Alexandra A and Grigorieva, Irina V and Mishchenko, Artem and Principi, Alessandro and Fal'ko, Vladimir I and Ponomarenko, Leonid A and Geim, Andre K and Berdyugin, Alexey I},
  title = {Giant magnetoresistance of Dirac plasma in high-mobility graphene},
  year = {2023},
  arxiv = {2302.06863},
  doi = {10.48550/arxiv.2302.06863}
}
  2. P. Steiner, S. Adnan, M. Said Ergoktas, J. Barrier, X. Yu, V. Orts, G. Bakan, J. Aze, Y. Malevich, K. Wang, P. Cataldi, M. Bisset, S. Balci, S. Suzer, M. Khafizov, and C. Kocabas, Electrically Controlled Heat Transport in Multilayer Graphene, (2022). [arXiv:2202.10342] [DOI] 
    @unpublished{steiner2022,
  author = {Steiner, Pietro and Adnan, Saqeeb and Said Ergoktas, Muhammed and Barrier, Julien and Yu, Xiaoxiao and Orts, Vincente and Bakan, Gokhan and Aze, Jonathan and Malevich, Yury and Wang, Kaiyuan and Cataldi, Pietro and Bisset, Mark and Balci, Sinan and Suzer, Sefik and Khafizov, Marat and Kocabas, Coskun},
  title = {Electrically controlled heat transport in multilayer graphene},
  year = {2022},
  arxiv = {2202.10342},
  doi = {10.48550/arxiv.2202.10342}
}
Peer-reviewed papers
  1. J. Barrier, R. E. Beal, A. Gold-Parker, J. A. Vigil, E. Wolf, L. Waquier, N. J. Weadock, Z. Zhang, L. T. Schelhas, A. F. Nogueira, M. D. McGehee, and M. F. Toney, Compositional Heterogeneity In Cs1-yFayPb(I1-xBrx) 3 Perovskite Films and Its Impact on Phase Behavior, Energy and Environmental Science 12 (2021). [DOI] [PDF] [SI] 
    @article{barrierees2021,
  author = {Barrier, Julien and Beal, Rachel E and Gold-Parker, Aryeh and Vigil, Julian A and Wolf, Eli and Waquier, Louis and Weadock, Nicholas J and Zhang, Zihan and Schelhas, Laura T and Nogueira, Ana Flávia and McGehee, Michael D and Toney, Michael F},
  title = {Compositional Heterogeneity in
             Cs1-yFayPb(I1-xBrx)
             3 Perovskite Films and its Impact on Phase Behavior},
  year = {2021},
  journal = {Energy and Environmental Science},
  pages = {6394-6405},
  issue = {14},
  number = {12},
  doi = {10.1039/D1EE01184G}
}
  2. S. Xu, M. M. Al Ezzi, N. Balakrishnan, A. Garcia-Ruiz, B. Tsim, C. Mullan, J. Barrier, N. Xin, B. A. Piot, T. Taniguchi, K. Watanabe, A. Carvalho, A. Mishchenko, A. K. Geim, V. I. Fal’ko, S. Adam, A. H. Castro Neto, K. S. Novoselov, and Y. Shi, Tuneable Van Hove Singularities and Correlated States in Twisted Monolayer-Bilayer Graphene, Nature Physics 17, 619 (2021). [arXiv:2004.15040] [DOI] 
    @article{xunatphys2021,
  author = {Xu, Shuigang and Al Ezzi, Mohammed M. and Balakrishnan, Nilanthy and Garcia-Ruiz, Aitor and Tsim, Bonnie and Mullan, Ciaran and Barrier, Julien and Xin, Na and Piot, Benjamin A. and Taniguchi, Takashi and Watanabe, Kenji and Carvalho, Alexandra and Mishchenko, Artem and Geim, Andre K. and Fal'ko, Vladimir I. and Adam, Shaffique and Castro Neto, Antonio Helio and Novoselov, Kostya S. and Shi, Yanmeng},
  title = {Tuneable van Hove Singularities and Correlated States in Twisted
           Monolayer-Bilayer Graphene},
  journal = {Nature Physics},
  volume = {17},
  pages = {619--626},
  year = {2021},
  arxiv = {2004.15040},
  doi = {10.1038/s41567-021-01172-9}
}
  3. J. Barrier, P. Kumaravadivel, R. Krishna-Kumar, L. A. Ponomarenko, N. Xin, M. Holwill, C. Mullan, M. Kim, R. V. Gorbachev, M. D. Thompson, J. R. Prance, T. Taniguchi, K. Watanabe, I. V. Grigorieva, K. S. Novoselov, A. Mishchenko, V. I. Fal’ko, A. I. Berdyugin, and A. K. Geim, Long-Range Ballistic Transport of Brown-Zak Fermions in Graphene Superlattices, Nature Communications 11, 5756 (2020). [arXiv:2006.15040] [DOI] [PDF] [SI] 
    @article{barriernatcomms2020,
  title = {Long-range ballistic transport of Brown-Zak fermions in graphene
           superlattices},
  author = {Barrier, Julien and Kumaravadivel, Piranavan and Krishna-Kumar, Roshan and Ponomarenko, Leonid A. and Xin, Na and Holwill, Matthew and Mullan, Ciaran and Kim, Minsoo and Gorbachev, Roman V. and Thompson, Michael D. and Prance, Jonathan R. and Taniguchi, Takashi and Watanabe, Kenji and Grigorieva, Irina V. and Novoselov, Kostya S. and Mishchenko, Artem and Fal'ko, Vladimir I. and Berdyugin, Alexey I. and Geim, Andre K.},
  journal = {Nature communications},
  volume = {11},
  pages = {5756},
  year = {2020},
  publisher = {Nature Publishing Group},
  doi = {10.1038/s41467-020-19604-0},
  arxiv = {2006.15040}
}
  4. Y. Shi, S. Xu, Y. Yang, S. Slizovskiy, S. V. Morozov, S.-K. Son, S. Ozdemir, C. Mullan, J. Barrier, J. Yin, A. I. Berdyugin, B. A. Piot, T. Taniguchi, K. Watanabe, V. I. Fal’ko, K. S. Novoselov, A. K. G. Geim, and A. Mishchenko, Electronic Phase Separation in Multilayer Rhombohedral Graphite, Nature 584, 210 (2020). [arXiv:1911.04565] [DOI] 
    @article{shinature2020,
  title = {Electronic phase separation in multilayer rhombohedral graphite},
  author = {Shi, Yanmeng and Xu, Shuigang and Yang, Yaping and Slizovskiy, Sergey and Morozov, Sergei V. and Son, Seok-Kyun and Ozdemir, Servet and Mullan, Ciaran and Barrier, Julien and Yin, Jun and Berdyugin, Alexei I. and Piot, Benjamin A. and Taniguchi, Takashi and Watanabe, Kenji and Fal'ko, Vladimir I. and Novoselov, Kostya S. and Geim, Andre K. Geim and Mishchenko, Artem},
  journal = {Nature},
  volume = {584},
  pages = {210--214},
  year = {2020},
  publisher = {Nature Publishing Group},
  doi = {10.1038/s41586-020-2568-2},
  arxiv = {1911.04565}
}
  5. R. E. Beal, N. Z. Hagström, J. Barrier, A. Gold-Parker, R. Prasanna, K. A. Bush, D. Passarello, L. T. Schelhas, K. Brüning, C. J. Tassone, H.-G. Steinrück, M. D. McGehee, M. F. Toney, and A. F. Nogueira, Structural Origins of Light-Induced Phase Segregation In Organic-Inorganic Halide Perovskite Photovoltaic Materials, Matter 2, 207 (2020). [DOI] 
    @article{bealmatter2020,
  title = {Structural origins of light-induced phase segregation in
           organic-inorganic halide perovskite photovoltaic materials},
  author = {Beal, Rachel E. and Hagström, Nanna Zhou and Barrier, Julien and Gold-Parker, Aryeh and Prasanna, Rohit and Bush, Kevin A. and Passarello, Donata and Schelhas, Laura T. and Brüning, Karsten and Tassone, Christopher J. and Steinrück, Hans-Georg and McGehee, Michael D. and Toney, Michael F. and Nogueira, Ana Flávia},
  journal = {Matter},
  volume = {2},
  issue = {1},
  pages = {207-219},
  year = {2020},
  doi = {10.1016/j.matt.2019.11.001}
}
Peer-reviewed conference abstracts
  1. J. Barrier, A. Berdyugin, P. Kumaravadivel, N. Xin, J. Prance, M. Kim, R. Jalil, R. Krishna Kumar, S. Islam, T. Taniguchi, K. Watanabe, and A. K. Geim, in Bulletin of the American Physical Society (APS March, Chicago, 2022). [url]
  2. A. Berdyugin, S. Xu, J. Barrier, M. Kim, N. Xin, Y. Shi, T. Taniguchi, K. Watanabe, and A. K. Geim, in Bulletin of the Americal Physical Society (APS March, Chicago, 2022). [url]
  3. J. Barrier, S. Xu, Y. Shi, M. Kim, V. I. Fal’ko, A. K. Geim, and K. S. Novoselov, Tunable Correlated States, Topological Flat Bands and Anomalous Hall Effect in Twisted Monolayer-Bilayer Graphene, in CMQM 2021 (Online, 2021). [url]
  4. J. Barrier, A. I. Berdyugin, P. Kumaravadivel, V. I. Fal’ko, and A. K. Geim, Long-Range Ballistic Transport of Brown-Zak Fermions in Graphene Superlattices, in Bulletin of the American Physical Society (APS March, Online, 2021). [url]
  5. J. Barrier, A. I. Berdyugin, P. Kumaravadivel, V. I. Fal’ko, and A. K. Geim, Ballistic Transport in the Magnetic Bloch States of Graphene Superlattices, in Graphene Conference (Grenoble, France, 2020). Best Talk Prize. [url]
  6. J. Barrier, A. I. Berdyugin, P. Kumaravadivel, T. Taniguchi, K. Watanabe, V. I. Fal’ko, and A. K. Geim, Direct Observation of Brown-Zak Mini-Bands in Graphene Superlattices, in Graphene Week, Graphene Flagship (Helsinki, Finland, 2019).
  7. M. F. Toney, R. E. Beal, J. Barrier, H.-G. Steinrück, M. D. McGehee, and A. F. Nogueira, Structural and Mechanistic Origins of Light-Induced Phase Segregation in Organic- Inorganic Halide Perovskite Photovoltaic Materials, in RSC MC 14 (Birmingham, UK, 2019).
  8. J. Barrier, A. Gold-Parker, E. Wolf, R. E. Beal, M. D. McGehee, and M. F. Toney, Tetragonal to Cubic Phase Transition In FA1-xCsxPb(I1-yBry)3: Temperature Dependance and Impact on Band Gap, in MRS Fall (Boston, MA, USA, 2018). [url]

Invited Talks

  1. Unidimensional Andreev bound states along quantum Hall edges, National Physical Laboratory, Teddington, UK, 17 February 2023;
  2. Unidimensional Andreev bound states along quantum Hall edges, Inst. of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe, Germany, 30 November 2022;
  3. Inducing topological superconductivity in twisted bilayer graphene, Correlated van der Waals heterostructures momentum research group, Dept. of Physics, Budapest University of Technology and Economics, Budapest, Hungary, 19 October 2022;
  4. Proximity superconductivity in twisted bilayer graphene, National Graphene Istitute, Manchester, 25 February 2022;
  5. , Impact Factory, Impact Hub Basel, Switzerland, 2 November 2021;
  6. Ballistic transport of Brown-Zak fermions, Low Temperature Physics group, Lancaster University, 11 September 2020;
  7. Ultra-low temperatures properties of Brown-Zak fermions and degeneracy lifting, Oxford Instruments Nanoscience Virtual Roadshow, 13 July 2020;
  8. Unravelling properties of Brown-Zak fermions at ultra-low temperatures, Oxford Instruments Nanoscience Virtual Roadshow, 2 July 2020;
  9. Ballistic transport in the magnetic Bloch states of graphene superlattices, National Graphene Institute, Manchester, 17 April 2020;
  10. Novel quantum phenomena in graphene, Trophée des Ingénieurs du Futur, Paris, 3 December 2019;
  11. Quantum electrons to the naked eye, Pint of Science, Manchester, 21 May 2019;
  12. Phase transition in mixed halide perovskites, impact on band-gap, Stanford Synchrotron Radiation Lightsource, Menlo Park, 24 August 2018;
  13. Encapsulation of flexible electronic devices, Laboratoire de Chimie - ENS de Lyon, Lyons, 22 December 2018;
  14. Gas barrier adhesives for encapsulation of organic and perovskite solar cells, LMPO CEA Liten, Chambéry, 19 December 2017;
  15. Jappix, free social network, Université de Genève, Geneva, 10 July 2012;
  16. Le web social, ISEN, Toulon, 28 April 2012;
  17. Réseaux sociaux libres, Unistra, Strasbourg, 12 July 2011;
  18. Jappix, réseau social libre, FOL83, Toulon, 15 January 2011;
  19. Jappix, un micro-réseau social libre, Polytech Nice, Sophia-Antipolis, 27 November 2010;
  20. Jappix, ENSEIRB, Bordeaux, 9 July 2010.

Press

Newspapers
  • New family of quasiparticles appears in graphene, 30 November 2020. Reported by Isabelle Dumé, Physics World. U.K.
  • Graphene researchers throw physics out the window, 16 November 2020. Reported by Sarah Lawton, Laboratory News. U.K.
  • Poursuivre sa thèse confiné(e), issue 59, September 2020. Reported by Lilia Bouraoui, 10 rue V@uquelin - Le bulletin d'ESPCI Alumni. France.
  • Thophée des ingénieurs du futur : lauréats et nommés dans la catégorie Recherche, 23 December 2019. Reported by Manuel Moragues, Industrie & Technologies. France.
  • Julien Barrier, l'électron libre, 5 December 2019. Reported by Olivier James, L'Usine Nouvelle. France.
  • Découvrez le monde le l’informatique libre. 27 April 2012. Reported by Myriam Tricocci Robert, Metro Toulon. France.
  • Informatique : la liberté à portée de clic. 14 January 2011. Reported by Thierry Turpin, La Marseillaise. France.
  • Actualités locales, 31 August 2010. Reported by Jacky Laurent, Var Matin La Seyne-sur-Mer. France.
Radio
  • Cyber Culture. 27 Septembre 2014, 2:00 PM, Radio Ici & Maintenant FM 95.2 MHz, Paris, France. Produced by Olivier Piquepé. 3h30’.
  • Jappix. La Voix du Libre, 13 July 2011, 9:30 AM, Radio RMLL (web), Québec, Canada. Produced by Yannick Pavard. 19’.
  • Morning News, 10 January 2010, 7:30 AM, France Bleu Provence FM 109.2 MHz, Toulon, France. 4’
Interviews
  • Tour du monde des campus en temps de crise 24 June 2021. Reported by Zoe Courtois. AEF Info France.
  • A research story: advancing mesoscopic physics 27 November 2020. Reported by Sarah Lawton. Laboratory News. U.K.
  • “Nous voulons garantir les libertés des utilisateurs.” 29 April 2012. Reported by David Latour. Var Matin Toulon. France.
  • Jappix, interview de Julien Barrier Dossier spécial Tchat, web & messagerie, October 2010. Reported by Aline Hof. Linux Pratique Essentiel. Issue 16. pages 5–7. France.

Personal

  • Born in January 1994 in Paris, France.
  • Speaks French (mother tongue), English (bilingual), German (conversational)
  • Hobbies comprise sailing, skiing, hiking, bike riding & cooking.
  • Current address:
    National Graphene Institute, office 1.006
    The University of Manchester
    Manchester M13 9PL, UK.