RESEARCH INTERESTS

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My research focuses on unraveling electronic and magnetic phenomena of a class of solids known as 'quantum materials'. Among these, I have extensively investigated unconventional superconductors, low-dimensional conductors (including thermoelectric cobalt oxides, graphite, nickel pnictides), and diverse magnetic systems (quantum spin ladders, frustrated systems, single-molecule magnets, antiferromagnetic spintronics). My primary technique is nuclear magnetic resonance (NMR) that I regularly use in conjunction with extremely intense magnetic fields (up to 45 T) to discover, study and control collective electron behavior including quantum spin liquids, spin-stripe glasses, charge density waves and electron nematic phases. I am particularly interested in the interplay, and the competition, between such phases and superconductivity as well as in the effect of disorder in these systems.

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SELECTED PUBLICATIONS

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• Competing orders linked to the pseudogap phase in La-based cuprates (Frachet et al. Nat. Physics 2020)

• Nematic fluctuations locally pinned by quenched disorder in a Fe-based superconductor (Iye et al. J. Phys. Soc. Jpn. 2015)

• Short-range CDW order pinned by disorder in YBCO (Wu et al. Nat. Commun. 2015)

• Long-range CDW order emerging from vortex cores in YBCO (Wu et al. Nat. Commun. 2013)

• Discovery of a charge-density wave competing with high Tc superconductivity in YBCO (Wu et al. Nature 2011)

• Coexistence of magnetic order and superconductivity in Fe pnictides (Julien et al. Europhys. Lett. 2009)

• Coupled ordering of electrons and ionic vacancies in a thermoelectric oxide (Julien et al. Phys. Rev. Lett. 2008)

• Formation of antiferromagnetic droplets around non-magnetic impurities in a cuprate superconductor (Julien et al. Phys. Rev. Lett. 2000)

• Antiferromagnetic striped glass coexisting with superconductivity in a cuprate (Julien et al. Phys. Rev. Lett. 1999)

• Gapped-singlet, Luttinger liquid and quantum critical phases of a quantum spin ladder in a magnetic field (Chaboussant et al. Phys. Rev. Lett. 1998)

• Connection between magnetic fluctuations, superexchange & superconductivity in high Tc cuprates (Julien et al. Phys. Rev. Lett. 1996)