About

Michael Crommie received a B.S. degree in physics from UCLA in 1984 and his Ph.D. from UC Berkeley in 1991. He was a postdoctoral researcher at IBM Almaden for two years before becoming an Assistant Professor in the Physics Department at Boston University in 1994. He moved his laboratory to the UC Berkeley Physics Department in June 1999 and joined the Berkeley faculty as an Associate Professor. His main research interests lie in exploring the local electronic, magnetic, and mechanical properties of atomic and molecular structures at surfaces. He is interested in studying how local interactions between atomic-scale structures affect their microscopic behavior and how quantum mechanical effects might influence nanodevice behavior in very small structures. His primary experimental tool is scanned probe microscopy, which he uses to fabricate atomic-scale structures and probe them spectroscopically. His research projects include atomic manipulation using scanning tunneling microscopy, exploring and modifying carbon nanostructures such as buckyballs, nanotubes, and graphene at the single atom/molecule level, investigating spin-based nanostructures and quantum spin effects, creating molecular machines from molecular-mechanical building blocks, and exploring nano-photovoltaics for energy conversion. Crommie has received awards including a National Science Foundation Young Investigator Award, the AAAS Newcomb Cleveland Prize, and a Sloan Foundation Fellowship.

Research topics

• Condensed matter physics
• Physics
• Computer Science
• Quantum mechanics
• Materials science
• Nanotechnology
• Crystallography
• Chemistry
• Chemical engineering
• Optics
• Optoelectronics
• Nuclear magnetic resonance
• Physical chemistry
• Organic chemistry
• Metallurgy

Selected publications

• Mott and generalized Wigner crystal states in WSe2/WS2 moiré superlattices

  Nature · 255 citations

  • Computer Science
  • Condensed matter physics
  • Materials science

  Abstract Moiré superlattices can be used to engineer strongly correlated electronic states in two-dimensional van der Waals heterostructures, as recently demonstrated in the correlated insulating and superconducting states observed in magic-angle twisted-bilayer graphene and ABC trilayer graphene/boron nitride moiré superlattices1–4. Transition metal dichalcogenide moiré heterostructures provide another model system for the study of correlated quantum phenomena5 because of their strong light–matter interactions and large spin–orbit coupling. However, experimental observation of correlated insulating states in this system is challenging with traditional transport techniques. Here we report the optical detection of strongly correlated phases in semiconducting WSe2/WS2 moiré superlattices. We use a sensitive optical detection technique and reveal a Mott insulator state at one hole per superlattice site and surprising insulating phases at 1/3 and 2/3 filling of the superlattice, which we assign to generalized Wigner crystallization on the underlying lattice6–11. Furthermore, the spin–valley optical selection rules12–14 of transition metal dichalcogenide heterostructures allow us to optically create and investigate low-energy excited spin states in the Mott insulator. We measure a very long spin relaxation lifetime of many microseconds in the Mott insulating state, orders of magnitude longer than that of charge excitations. Our studies highlight the value of using moiré superlattices beyond graphene to explore correlated physics.

  DOI

• Pseudo–Jahn–Teller Distortion in a One-Dimensional π-Conjugated Polymer

  Journal of the American Chemical Society · 2026-02-14 · 2 citations

  articleOpen accessSenior authorCorresponding

  Structural distortions in low-dimensional π-conjugated systems profoundly influence their electronic properties, but the control of such behavior in laterally extended systems remains challenging. Here we demonstrate that a one-dimensional conjugated polymer─poly-(difluorenoheptalene-ethynylene) (PDFHE)─undergoes a pronounced out-of-plane backbone distortion, equivalent to a spontaneous symmetry breaking (SSB) of its mirror symmetry. We synthesized PDFHE on noble metal surfaces and characterized its structure and electronic states using low-temperature scanning tunneling microscopy (STM). Rather than adopting a planar, high-symmetry conformation, PDFHE relaxes into nonplanar isomers stabilized by a pseudo–Jahn–Teller (PJT) distortion having mirror-odd out-of-plane character. The distortion lowers the total energy and increases the band gap, providing a concise rationale for the observed symmetry breaking. Density functional theory calculations corroborate these findings, providing a microscopic explanation for the SSB. Our results show that even in mechanically robust extended π-systems, subtle electron–lattice coupling can spontaneously drive significant structural rearrangements, even in mechanically robust extended π-systems.

  PublisherOA PDFDOI

• Coupling of Nondegenerate Topological Modes in Nitrogen Core-Doped Graphene Nanoribbons

  ACS Nano · 2025-03-27 · 5 citations

  articleOpen accessCorresponding

  Nitrogen core-doping of graphene nanoribbons (GNRs) allows trigonal planar carbon atoms along the backbone of GNRs to be substituted by higher-valency nitrogen atoms. The excess valence electrons are injected into the π-orbital system of the GNR, thereby changing not only its electronic occupation but also its topological properties. We have observed this topological change by synthesizing dilute nitrogen core-doped armchair GNRs with a width of five atoms (N2-5-AGNRs). The incorporation of pairs of trigonal planar nitrogen atoms results in the emergence of topological boundary states at the interface between doped and undoped segments of the GNR. These topological boundary states are offset in energy by approximately ΔE = 300 meV relative to the topological end states at the termini of finite 5-AGNRs. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal that for finite GNRs the two types of topological states can interact through a linear combination of orbitals, resulting in a pair of asymmetric hybridized states. This behavior is captured by an effective Hamiltonian of nondegenerate diatomic molecules, where the analogous interatomic hybridization interaction strength is tuned by the distance between GNR topological modes.

  PublisherOA PDFDOI

• Competition between excitonic insulators and quantum Hall states in correlated electron–hole bilayers

  Nature Materials · 2025-08-25 · 5 citations

  articleOpen access
  PublisherOA PDFDOI

• Spin Frustration and Unconventional Surface Spin Canting State in Van der Waals Ferromagnet/Antiferromagnet Heterostructures

  Advanced Materials · 2025-08-01 · 2 citations

  articleOpen access

  Abstract Atomically flat surfaces of van der Waals (vdW) materials pave an avenue for addressing a long‐standing fundamental issue of how a compensated antiferromagnet (AFM) surface frustrates a ferromagnetic (FM) overlayer in FM/AFM heterostructures. We investigate Fe 5 GeTe 2 /NiPS 3 vdW heterostructures by characterizing AFM and FM spins separately. We find that in‐plane zig‐zag AFM NiPS 3 develops three equivalent AFM domains, which are robust against external magnetic field and magnetic coupling with Fe 5 GeTe 2 . Moreover, evidence is provided of in‐plane‐AFM‐induced perpendicular magnetic anisotropy (PMA) in adjacent Fe 5 GeTe 2 , and an unconventional out‐of‐plane surface spin canting state with the Fe 5 GeTe 2 spins spatially turn from out‐of‐plane direction near the interface to in‐plane direction away from the interface in Fe 5 GeTe 2 /NiPS 3 . The out‐of‐plane surface spin canting is a unique property of spin frustration in vdW magnetic heterostructures.

  PublisherOA PDFDOI

• Imaging Electron-Hole Asymmetry in the Quantum Melting of Generalized Wigner Crystals

  ArXiv.org · 2025-12-18

  preprintOpen accessSenior author

  Two-dimensional moiré materials provide a versatile platform to explore phase transitions in strongly correlated systems. Using scanning tunneling microscopy (STM) we have imaged the density-driven melting of generalized Wigner crystals (GWCs) and Mott insulators (MIs) in electron-doped, near-60° twisted MoSe2 bilayers featuring a triangular moiré superlattice. We observe striking electron-hole asymmetry in GWC melting: hole-doped GWCs yield interaction-driven disordered states whereas electron-doped GWCs melt into delocalized liquid-like states. This asymmetry arises from the broken particle-hole symmetry of the moiré superlattice, which produces electron and hole Fermi pockets with different momentum geometries upon GWC condensation. MI states melt without such asymmetry, consistent with the absence of a symmetry-breaking density modulation. This work provides direct visualization of the novel emergent phases that appear as GWCs undergo quantum melting transitions.

  PublisherOA PDFDOI

• Spin frustration and unconventional spin twisting state in van der Waals ferromagnet/antiferromagnet heterostructures

  ArXiv.org · 2025-01-28

  preprintOpen access

  Atomically flat surfaces of van der Waals (vdW) materials pave an avenue for addressing a long-standing fundamental issue of how a perfectly compensated antiferromagnet (AFM) surface frustrates a ferromagnetic (FM) overlayer in FM/AFM heterostructures. By revealing the AFM and FM spin structures separately in vdW Fe5GeTe2/NiPS3 heterostructures, we find that C-type in-plane AFM NiPS3 develops three equivalent AFM domains which are robust against external magnetic field and magnetic coupling with Fe5GeTe2. Consequently, spin frustration at the Fe5GeTe2/NiPS3 interface was shown to develop a perpendicular Fe5GeTe2 magnetization in the interfacial region that switches separately from the bulk of the Fe5GeTe2 magnetizations. In particular, we discover an unconventional spin twisting state that the Fe5GeTe2 spins twist from perpendicular direction near the interface to in-plane direction away from the interface in Fe5GeTe2/NiPS3. Our finding of the twisting spin texture is a unique property of spin frustration in van der Waals magnetic heterostructures.

  PublisherOA PDFDOI

• <i>In-Situ</i> Dynamics of Moiré Superlattice Epitaxy as a Platform for Site-Selective Adhesion and Growth

  Microscopy and Microanalysis · 2025-07-01

  article
  PublisherDOI

• Graphene-driven correlated electronic states in one dimensional defects within WS2

  Nature Communications · 2025-07-01 · 1 citations

  articleOpen access

  Abstract Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of one-dimensional defects hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate require cross-correlative investigation. Here, we study TLL formation within defectively engineered WS 2 atop graphene, where band structure and the atomic environment is visualized with nano angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and spectroscopy, and non-contact atomic force microscopy. Correlations between the local density of states and electronic band dispersion elucidated the electron transfer from graphene into a TLL hosted by one-dimensional metal (1DM) defects. It appears that the vertical heterostructure with graphene and the induced charge transfer from graphene into the 1DM is critical for the formation of a TLL.

  PublisherOA PDFDOI

• Figure 2 Training Curves

  ArXiv.org · 2025-10-13

  preprintOpen accessSenior author

  Electron Wigner solids (WSs)1-12 provide an ideal system for understanding the competing effects of electron-electron and electron-disorder interactions, a central unsolved problem in condensed matter physics. Progress in this topic has been limited by a lack of single-defect-resolved experimental measurements as well as accurate theoretical tools to enable realistic experiment-theory comparison. Here we overcome these limitations by combining atomically-resolved scanning tunneling microscopy (STM) with quantum Monte Carlo (QMC) simulation of disordered 2D electron WSs. STM was used to image the electron density ($n_e$) dependent evolution of electron WSs in gate-tunable bilayer MoSe$_2$ devices with varying long-range ($n_\mathrm{LR}$) and short-range ($n_\mathrm{SR}$) disorder densities. These images were compared to QMC simulations using realistic disorder maps extracted from experiment, thus allowing the roles of different disorder types to be disentangled. We identify two distinct physical regimes for disordered electron WSs that depend on the magnitude of $n_\mathrm{SR}$. For $n_\mathrm{SR} \lesssim n_e$ the WS behavior is dominated by long-range disorder and features extensive mixed solid-liquid phases, a new type of re-entrant melting-crystallization, and prominent Friedel oscillations. In contrast, when $n_\mathrm{SR} \gg n_e$ these features are suppressed and a more robust amorphous WS phase emerges that persists to higher $n_e$, highlighting the importance of short-range disorder in this regime. Our work establishes a new framework for studying disordered quantum solids via a combined experimental-theoretical approach.

  PublisherOA PDFDOI

Recent grants

• NIRT: Synthesis and Control of Molecular Machines

  NSF · $1.4M · 2002–2008

• Interactive Microscopy of Hybrid Scattering Structures

  NSF · $750k · 2018–2022

• Correlating Local Defect Structure with Dynamical Response in Graphene

  NSF · $324k · 2012–2015

• Imaging Correlated Electron States in Single-layer Field-Effect Transistors

  NSF · $435k · 2022–2025

• Interactive Microscopy of Graphene Nanostructures

  NSF · $457k · 2009–2012

Frequent coauthors

• Alex Zettl

  Kavli Energy NanoScience Institute

  534 shared

• Feng Wang

  University of California, Berkeley

  359 shared

• Felix R. Fischer

  Lawrence Berkeley National Laboratory

  248 shared

• Steven G. Louie

  Lawrence Berkeley National Laboratory

  229 shared

• Hsin‐Zon Tsai

  Lawrence Berkeley National Laboratory

  170 shared

• Kenji Watanabe

  National Institute for Materials Science

  162 shared

• Takashi Taniguchi

  161 shared

• Salman Kahn

  Lawrence Berkeley National Laboratory

  131 shared

Awards & honors

• National Science Foundation Young Investigator Award (1994)
• AAAS Newcomb Cleveland Prize for 1993-94
• Sloan Foundation Fellowship (1997)