Patrick E. Hopkins
· Whitney Stone Professor of Engineering Professor, Mechanical and Aerospace Engineering Professor, Materials Science and Engineering, by courtesy Professor, Physics, by courtesyVerifiedUniversity of Virginia · Materials Science and Engineering
Active 1971–2026
About
Professor Patrick E. Hopkins is the Whitney Stone Professor in Engineering at the University of Virginia, primarily appointed in the Department of Mechanical and Aerospace Engineering, with courtesy appointments in the Departments of Materials Science and Engineering and Physics. He serves as the Principal Investigator and co-director of the ExSiTE Lab. Patrick earned his Ph.D. in Mechanical and Aerospace Engineering from the University of Virginia in 2008, after completing a B.S. in Mechanical Engineering and a B.A. in Physics at UVA in 2004. Following his doctoral studies, he was a Harry S. Truman Postdoctoral Fellow at Sandia National Laboratories in Albuquerque, New Mexico, from 2008 to 2011. In addition to his academic roles, Patrick Hopkins is the Chief Science Officer and co-founder of Laser Thermal, a Charlottesville, Virginia-based company specializing in thermal conductivity measurement equipment and services. His research and professional contributions have been recognized through numerous awards and honors, including being named a Fellow of the American Association for the Advancement of Science (AAAS) in 2024 and a Fellow of the American Society of Mechanical Engineers (ASME) in 2019. He has also been a National Finalist for the Blavatnik Award for Young Scientists multiple times and has received prestigious awards such as the ASME Gustus L. Larson Memorial Award, the Presidential Early Career Award for Scientists and Engineers (PECASE), and Young Investigator Awards from the Office of Naval Research and the Air Force Office of Scientific Research. His career reflects significant contributions to research in mechanical and aerospace engineering, particularly in thermal sciences.
Research topics
- Materials science
- Composite material
- Nanotechnology
- Chemistry
- Thermodynamics
- Optoelectronics
- Chemical physics
- Condensed matter physics
- Optics
- Computational chemistry
- Crystallography
- Physical chemistry
- Electrical engineering
- Organic chemistry
- Metallurgy
- Inorganic chemistry
Selected publications
Tailoring phonon-driven responses in α-MoO3 through isotopic enrichment
arXiv (Cornell University) · 2026-01-05
preprintOpen accessThe implementation of polaritonic materials into nanoscale devices requires selective tuning of parameters to realize desired spectral or thermal responses. One robust material is α-MoO3, which as an orthorhombic crystal boasts three distinct phonon dispersions, providing three polaritonic dispersions of hyperbolic phonon polaritons (HPhPs) across the mid-infrared (MIR). Here, the tunability of both optical and thermal responses in isotopically enriched α-MoO3 (98MoO3, Mo18O3 and 98Mo18O3) are explored. A uniform ~5 % spectral redshift from 18O enrichment is observed in both Raman- and IR-active TO phonons. Both the in- and out-of-plane thermal conductivities for the isotopic variations are reported. Ab initio calculations both replicate experimental findings and analyze the select-mode three-phonon scattering contributions. The HPhPs from each isotopic variation are probed with s-SNOM and their Q- factors are reported. A Q-factor maxima increase of ~50 % along the [100] in the RB2 and ~100 % along the [001] in the RB3 are reported for HPhPs supported in 98Mo18O3. Observations in both real and Fourier space of higher-order HPhP modes propagating in single slabs of isotopically enriched α-MoO3 without the use of a subdiffractional surface scatterer are presented here. This work illustrates the tunability of α-MoO3 for thermal and nanophotonic applications.
Tailoring phonon-driven responses in α-MoO3 through isotopic enrichment
ArXiv.org · 2026-01-05
articleOpen accessThe implementation of polaritonic materials into nanoscale devices requires selective tuning of parameters to realize desired spectral or thermal responses. One robust material is α-MoO3, which as an orthorhombic crystal boasts three distinct phonon dispersions, providing three polaritonic dispersions of hyperbolic phonon polaritons (HPhPs) across the mid-infrared (MIR). Here, the tunability of both optical and thermal responses in isotopically enriched α-MoO3 (98MoO3, Mo18O3 and 98Mo18O3) are explored. A uniform ~5 % spectral redshift from 18O enrichment is observed in both Raman- and IR-active TO phonons. Both the in- and out-of-plane thermal conductivities for the isotopic variations are reported. Ab initio calculations both replicate experimental findings and analyze the select-mode three-phonon scattering contributions. The HPhPs from each isotopic variation are probed with s-SNOM and their Q- factors are reported. A Q-factor maxima increase of ~50 % along the [100] in the RB2 and ~100 % along the [001] in the RB3 are reported for HPhPs supported in 98Mo18O3. Observations in both real and Fourier space of higher-order HPhP modes propagating in single slabs of isotopically enriched α-MoO3 without the use of a subdiffractional surface scatterer are presented here. This work illustrates the tunability of α-MoO3 for thermal and nanophotonic applications.
Physical Review Materials · 2026-05-20
articleOpen accessIn this work, we develop a rapid reactive vapor transport technique to efficiently utilize limited isotopically pure precursors, particularly gaseous $^{18}\mathrm{O}_{2}$, and synthesize mm-scale, high-quality isotope-enriched crystals within few-minute growth durations. We unlock this capability by using metallic molybdenum precursors with high source temperatures ($900{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$) and total pressures ($\ensuremath{\sim}1$ atm) to maximize precursor efficiency and yield. Subsequently, we grow $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Mo}{\mathrm{O}}_{3}$ single crystals with high and uniform enrichment levels of $^{98}\mathrm{Mo}$ and $^{18}\mathrm{O}$ isotopes in several different permutations. As probed by Raman spectroscopy, modest and significant phonon energy redshifts occur following $^{98}\mathrm{Mo}$ and $^{18}\mathrm{O}$ enrichment, respectively. By demonstrating control over both molybdenum and oxygen isotopic enrichments, we establish a powerful tool to advance nanophotonics and thermal management goals using $\ensuremath{\alpha}\text{\ensuremath{-}}\mathrm{Mo}{\mathrm{O}}_{3}$. This work is motivated by the possibility to enhance and engineer lattice vibrational mode phenomena including thermal conduction and hyperbolic phonon polariton dispersion---with particular interest in comparing the effects of light and heavy element enrichment.
Nature Communications · 2025-07-02 · 4 citations
articleOpen accessSenior authorInsulating materials featuring ultralow thermal conductivity for diverse applications also require robust mechanical properties. Conventional thinking, however, which correlates strong bonding with high atomic-vibration-mediated heat conduction, led to diverse weakly bonded materials that feature ultralow thermal conductivity and low elastic moduli. One must, therefore, search for strongly-bonded single crystals in which heat transport is impeded by other means. Here, we report intrinsic, glass-like, ultralow thermal conductivity and ultrahigh elastic-modulus/thermal-conductivity ratio in single-crystalline Ruddlesden-Popper Ban+1ZrnS3n+1, n = 2, 3, which are derivatives of BaZrS3. Their key features are strong anharmonicity and intra-unit-cell rock-salt blocks. The latter produce strongly bonded intrinsic superlattices, impeding heat conduction by broadband reduction of phonon velocities and mean free paths and concomitant strong phonon localization. The present study initiates a paradigm of “mechanically stiff phonon glasses”. Here, the authors report on the thermal and mechanical properties of Ruddlesden-Popper phases (Ban+1ZrnS3n+1, n = 2 and 3) of a perovskite chalcogenide (BaZrS3) that push to extreme limits and defy the century-old relation between thermal conductivity and interatomic bond strength.
Machine-Learning Molecular Dynamics for Insights into Vibrational Electron Energy Loss Spectroscopy
Microscopy and Microanalysis · 2025-07-01
articleTopology-Driven Vibrations in a Chiral Polar Vortex Lattice
arXiv (Cornell University) · 2025-09-13
preprintOpen accessThe ordering of magnetic or electric dipoles leading to real-space topological structures is at the forefront of materials research as their quantum mechanical nature often lends itself to emergent properties. Atomic lattice vibrations (phonons) are often a key contributor to the formation of long-range dipole textures based on ferroelectrics and impact the properties of the emergent phases. Here, using monochromated, momentum-resolved electron energy-loss spectroscopy (qEELS) with nanometer spatial resolution and meV-spectral-precision, we demonstrate that polar vortex lattices in PbTiO$_3$ spatially modulate the material's vibrational spectrum in patterns that directly reflect the overlying symmetry of the topological patterns. Moreover, by combining experiments with molecular dynamics simulations using machine learned potentials we reveal how these structures modify phonon modes across the vibrational spectrum. Beyond simple intensity modulation, we find that the chirality of the vortex topology imparts its unique symmetry onto phonons, producing a distinctive asymmetrical spectral shift across the vortex unit cell. Finally, the high spatial resolution of the technique enables topological defects to be probed directly, demonstrating a return to trivial PbTiO$_3$ modes at vortex dislocation cores. These findings establish a fundamental relationship between ferroelectric-ordering-induced topologies and phonon behavior, opening new avenues for engineering thermal transport, electron-phonon coupling, and other phonon-mediated properties in next-generation nanoscale devices.
Reduced thermal resistance of Al-rich AlGaN HEMTs via top-side diamond integration
APL Electronic Devices · 2025-12-01
articleOpen accessWe report back-end-of-line growth of nanocrystalline diamond (NCD) on ultrawide bandgap (UWBG) high Al content aluminum gallium nitride (AlGaN) channel high electron mobility transistors for thermal management. A thin (∼15 nm) silicon nitride (SiNx) interlayer was deposited to protect the device surface before performing a low temperature (500 °C) NCD growth process in an attempt to protect the gates on these fully fabricated devices. Notably, atomic force microscopy showed that the maximum lateral grain size exceeded 300 nm even though the film thickness was ∼250 nm. Comparing electrical (DC) performance before and after NCD growth, the gate leakage increased by ∼102 after NCD growth. Despite the lower NCD growth temperature, intermixing of the Ni and Au was observed in the Schottky gate metal stack; however, we believe there is another mechanism, possibly hydrogen-related, that is responsible for the measured increase in gate leakage. Regarding thermal management, the device-level thermal resistance (quantified using the average gate temperature rise measured by thermoreflectance imaging) was reduced by 29% through the incorporation of the top-side diamond film. Using time-domain thermoreflectance, the thermal conductivity of the ≈250 nm thick NCD film was measured to be 45 ± 25 W m−1 K−1. This is expected to be at least 5× greater than the thermal conductivity of the thin disordered AlGaN alloy. There could also be a coupled electrothermal component contributing to the reduced temperature rise from electric field spreading and consequent heat spreading. This study demonstrates a promising first step toward device-level thermal management of high power UWBG Al-rich AlGaN devices.
Nature Reviews Methods Primers · 2025-08-28 · 8 citations
articleSenior authorMechanical properties of compositionally modulated epitaxial VN(001)/VC(001) films
Acta Materialia · 2025-05-12 · 1 citations
articleEpitaxial growth and semiconductor properties of NiGa2O4 spinel for Ga2O3/NiO interfaces
ArXiv.org · 2025-12-23
articleOpen accessUnintentionally formed interfacial layers are ubiquitous in semiconductor devices that operate at extreme conditions. However, these layers' structure and properties often remain unknown due to the thinness of these naturally formed interphases. Here, we report on the intentional epitaxial growth and semiconductor properties of NiGa2O4 spinel layers that form at Ga2O3/NiO interfaces used in high-power and high-temperature electronic devices. Cubic spinel NiGa2O4 films of 10-50 nm thicknesses and low surface roughness (~ 2 nm) were grown using pulsed laser deposition at a substrate temperatures in the 300-900 °C range on α-Al2O3 and β-Ga2O3 substrates of different orientation. The optical absorption onset (3.6-3.9 eV) and thermal conductivity (4-9 W m-1 K-1) vary systematically with substrate temperature, consistent with theoretical predictions of varying Ni and Ga cation ordering on the spinel lattice. The valence band offset between NiGa2O4 and β-Ga2O3 is determined to be 1.8 eV. The NiGa2O4-based p-n heterojunction devices on Ga2O3 (001) substrates exhibit a rectification ratio of 10^8 (for +/-2V) and a turn-on voltage of 1.4 V, maintaining diode behavior up to 600 °C. These results highlight the potential of NiGa2O4 as a p-type interlayer in Ga2O3-based devices and shows a new approach to investigate such interfacial layers.
Recent grants
Enhanced conductance at interfaces by ballistic thermal injection
NSF · $459k · 2023–2026
NSF · $334k · 2017–2021
EAGER: Solid-state thermal switching
NSF · $234k · 2013–2016
Mitigation of Thermal Resistance in High Power Photodiodes as a Means to Increase Device Performance
NSF · $350k · 2015–2018
NSF · $482k · 2012–2016
Frequent coauthors
- 151 shared
John T. Gaskins
- 116 shared
Ashutosh Giri
University of Rhode Island
- 108 shared
John C. Duda
University of Virginia
- 87 shared
John A. Tomko
University of Virginia
- 82 shared
David H. Olson
Twin Cities Orthopedics
- 80 shared
Md Shafkat Bin Hoque
University of Virginia
- 80 shared
Jon F. Ihlefeld
University of Virginia
- 77 shared
Jeffrey L. Braun
Labs
Awards & honors
- Gustus L. Larson Memorial Award 2021
- Humboldt Research Fellowship for Experienced Researchers 202…
- Fellow of the American Society of Mechanical Engineers 2019
- ASME Bergles-Rohsenow Young Investigator Award in Heat Trans…
- National Finalist, Blavatnik Award for Young Scientists 2014
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