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  2. Xiaolong Liu

Xiaolong Liu

Assistant Professor, Department of Physics & Astronomy

Assistant Professor, Department of Physics & Astronomy

Office
435 Nieuwland Science Hall
Notre Dame, IN 46556
Phone
+1 574-631-6768
Email
xliu33@nd.edu

Liu Research Group Website

Research Interests

Our group investigates novel quantum states of matter at the atomic scale, alongside the development of new scanning probe microscopy techniques. We are particularly interested in Josephson physics and unconventional superconductivity that involves spin-triplet or mixed-parity pairing, Cooper-pair density waves and intertwined orders, as well as the coexistence of multiple superconducting condensates.

Experimental Approaches

We utilize spectroscopic imaging scanning tunneling microscopy (SI-STM) and scanned Josephson tunneling microscopy (SJTM) that operate below 0.3 K in magnetic fields up to 9 T. We perform experimental quantum simulation by crafting artificial structures via on-surface single atom/molecule manipulations. We synthesize and functionalize novel materials using in situ molecular beam epitaxy. We create 2D heterostructures via stacking in inert environments.

Honors and Activities

2025 Faculty Early Career Development Program (CAREER) award, NSF

2023 Ralph E. Powe Junior Faculty Enhancement Award, ORAU

2022 Blavatnik Regional Award for Young Scientists in the category of Physical Sciences & Engineering

2022 Young Scientist Prize in Low Temperature Physics by the International Union of Pure and Applied Physics (IUPAP)

Education

PhD, Northwestern University, 2018
BS, University of Science and Technology of China, 2013

Publications

Selected Publications

N. Sharma, M. Toole, J. McKenzie, S. Ran, and X. Liu, Atomic-scale Frustrated Josephson Coupling and Multi-condensate Visualization in FeSe. Nat. Mater. 24, 1709–1715 (2025) (Front Cover).
N. Sharma, M. Toole, J. McKenzie, F. Cheng, S.M. Thomas, P.F.S. Rosa, Y.-T. Hsu, and X. Liu, Observation of Persistent Zero Modes and Superconducting Vortex Doublets in UTe2. ACS Nano 19, 31539-31550 (2025).
Q. Gu, S. Wang, J. P. Carroll, K. Zhussupbekov, C. Broyles, S. Ran, N. P. Butch, S. Saha, J. Paglione, X. Liu, J.C. Séamus Davis, and D.-H. Lee, Pair Wavefunction Symmetry in UTe2 from Zero-Energy Surface State Visualization, Science 388, 938-944 (2025).
Q. Gu, J. P. Carroll, S. Wang, S. Ran, C. Broyles, H. Siddiquee, N. P. Butch, S. R. Saha, J. Paglione, J. C. Séamus Davis, and X. Liu, Detection of a pair density wave state in UTe2. Nature 618, 921–927 (2023).
X. Liu, Q. Li, Q. Ruan, B. I. Yakobson, and M. C. Hersam, Borophene synthesis beyond the single-atomic-layer Limit, Nat. Mater. 21, 35–40 (2022).
X. Liu, Y. X. Chong, R. Sharma, and J.C. Séamus Davis, Discovery of a Cooper-pair density wave state in a transition-metal dichalcogenide, Science 372, 1447-1452 (2021).
X. Liu, Y. X. Chong, R. Sharma, and J.C. Séamus Davis, Atomic-scale visualization of electron fluid flow, Nat. Mater. 20, 1480–1484 (2021).X. Liu, M. C. Hersam, 2D materials for quantum information science, Nat. Rev. Mater. 4, 669–684 (2019) (Front Cover).
X. Liu, Z. Zhang, L. Wang, B. I. Yakobson, and M. C. Hersam, Intermixing and periodic self-assembly of borophene line defects, Nat. Mater. 17, 783–788 (2018).