Tyrel M. McQueen
· ProfessorVerifiedJohns Hopkins University · Physics
Active 2003–2026
About
Professor Tyrel M. McQueen is a researcher leading the McQueen Lab, part of the Quantum Materials Research Group. His work focuses on discovering new phenomena through the design and synthesis of novel materials, with particular emphasis on materials science, quantum materials, and their potential applications. His research includes advancing materials synthesis techniques and exploring the properties of quantum materials, as evidenced by his recent publications and presentations on superconductivity, ferromagnetism, and quantum electronic phenomena. Professor McQueen has contributed to the field through innovative approaches to materials discovery, including the development of gate-tunable ferromagnetism in semiconductor-Dirac semimetal heterojunctions and the exploration of field-free Josephson diode effects using Kagome Mott insulator barriers. He actively engages in scientific dissemination, participating in conferences such as the ACS Spring 2022 and NeurIPS 2025 Workshop AI4Mat, and is involved in educational outreach, including guided materials discovery and curriculum design. His work is recognized for its impact on the future of quantum materials synthesis and the broader field of materials science.
Research topics
- Condensed matter physics
- Physics
- Quantum mechanics
- Crystallography
- Computer Science
- Chemistry
- Atomic physics
- Mechanical engineering
- Biology
- Materials science
- Mathematics
- Bioinformatics
- Control engineering
- Optoelectronics
- Engineering
Selected publications
Advanced Electronic Materials · 2026-05-08
articleOpen accessABSTRACT Magnetic skyrmions are topologically protected spin states that hold promise for shaping the future of electronics. Despite impressive progress in skyrmion research, the microscopic mechanisms underlying skyrmion phase transitions at specific temperatures and magnetic fields remain elusive. In this work, we systematically study the isostructural centrosymmetric magnets GdRu 2 X 2 (X = Si and Ge) and the role of X‐ p orbitals in modifying magnetic exchange interactions. Electronic structure and exchange interaction evaluations reveal that the more extended Ge‐4 p versus Si‐3 p orbitals enhance competing exchange interactions in GdRu 2 Ge 2 , thereby manifesting the evolution condition of skyrmions in GdRu 2 X 2 . GdRu 2 Ge 2 single crystals exhibit two high‐entropy regions associated with skyrmion phases at 0.9 T ≤ µ 0 H ≤ 1.2 T and 1.3 T ≤ µ 0 H ≤ 1.7 T, 2 K ≤ T ≤ 30 K—lower field and higher temperature conditions than those in the Si counterpart. Transport measurements reveal the topological Hall effect, validating the topologically nontrivial spin textures and Berry curvature. Our work bridges the gap between skyrmion discovery and material design by demonstrating, for the first time, how atomic‐scale control of exchange interactions enables tunable skyrmion phase transitions, making a significant step toward stabilizing skyrmions at desired temperatures and magnetic fields.
Stripping Symmetry: Electrochemical Oxidation to a Superconducting Polar Metal in Au2Pb0.914P2
ArXiv.org · 2026-04-20
articleOpen accessPolar metals and noncentrosymmetric superconductors are exceptionally rare, yet their broken inversion symmetry can give rise to emergent electronic phenomena including mixed singlet-triplet superconducting pairing. As only a few such materials have been found among known compounds, accessing new examples requires synthetic strategies that go beyond conventional crystal growth. Here, we use electrochemical topotactic deintercalation to remove Pb from the centrosymmetric parent compound Au$_2$PbP$_2$, producing the polar metal Au$_2$Pb$_{0.914}$P$_2$. Unlike conventional chemical doping, this transformation actively drives structural symmetry-breaking: the partial removal of Pb triggers a cooperative electronic and geometric rearrangement, mediated by a second-order Jahn-Teller effect and stereochemically active lone pairs, that locks the product into a polar, noncentrosymmetric superspace group Ama2(01g)ss0. We solve the complete (3+1)D modulated structure by synchrotron single-crystal X-ray diffraction and confirm the polar assignment through nonlinear electronic transport. Below T$_c$ = 1.52 K, Au$_2$Pb$_{0.914}$P$_2$ becomes a type-II superconductor whose heat capacity and AC susceptibility both exhibit power-law behavior, suggestive of a gap structure governed by the broken inversion symmetry of the host lattice. This work establishes electrochemical oxidation as a rational route to metastable noncentrosymmetric superconductors through chemically directed symmetry-breaking.
ArXiv.org · 2026-03-06
articleOpen accessWe use molecular beam epitaxy to develop a gate tunable p-n heterojunction that interfaces a canonical Dirac semimetal, Cd$_3$As$_2$, and a ferromagnetic semiconductor, In$_{1-x}$Mn$_x$As, with perpendicular magnetic anisotropy. Measurements of the anomalous Hall effect in top-gated Cd$_3$As$_2$/In$_{1-x}$Mn$_x$As devices show that the ferromagnetic Curie temperature ($T_\mathrm{C}$) can be efficiently tuned using a modest gate voltage of $\sim 10$ V, corresponding to a sensitivity to electric field ($E$) of $ΔT_{\mathrm{C}}/ΔE \sim 10$ K/MV/cm). The voltage tuning of $T_\mathrm{C}$ saturates near the charge neutrality point of Cd$_3$As$_2$ and vanishes at positive gate voltage in appropriately designed heterostructures. This non-monotonic behavior cannot be explained solely by hole-mediated ferromagnetism in the In$_{1-x}$Mn$_x$As alone, suggesting an interaction between the Dirac semimetal and the ferromagnetic semiconductor. Our results identify Cd$_3$As$_2$/In$_{1-x}$Mn$_x$As heterojunctions as a potentially attractive platform for studying emergent phenomena arising from the interplay between broken symmetry, topology, and magnetism in a topological semimetal.
Open MIND · 2026-03-06
preprintWe use molecular beam epitaxy to develop a gate tunable p-n heterojunction that interfaces a canonical Dirac semimetal, Cd$_3$As$_2$, and a ferromagnetic semiconductor, In$_{1-x}$Mn$_x$As, with perpendicular magnetic anisotropy. Measurements of the anomalous Hall effect in top-gated Cd$_3$As$_2$/In$_{1-x}$Mn$_x$As devices show that the ferromagnetic Curie temperature ($T_\mathrm{C}$) can be efficiently tuned using a modest gate voltage of $\sim 10$ V, corresponding to a sensitivity to electric field ($E$) of $ΔT_{\mathrm{C}}/ΔE \sim 10$ K/MV/cm). The voltage tuning of $T_\mathrm{C}$ saturates near the charge neutrality point of Cd$_3$As$_2$ and vanishes at positive gate voltage in appropriately designed heterostructures. This non-monotonic behavior cannot be explained solely by hole-mediated ferromagnetism in the In$_{1-x}$Mn$_x$As alone, suggesting an interaction between the Dirac semimetal and the ferromagnetic semiconductor. Our results identify Cd$_3$As$_2$/In$_{1-x}$Mn$_x$As heterojunctions as a potentially attractive platform for studying emergent phenomena arising from the interplay between broken symmetry, topology, and magnetism in a topological semimetal.
Stripping Symmetry: Electrochemical Oxidation to a Superconducting Polar Metal in Au2Pb0.914P2
arXiv (Cornell University) · 2026-04-20
preprintOpen accessPolar metals and noncentrosymmetric superconductors are exceptionally rare, yet their broken inversion symmetry can give rise to emergent electronic phenomena including mixed singlet-triplet superconducting pairing. As only a few such materials have been found among known compounds, accessing new examples requires synthetic strategies that go beyond conventional crystal growth. Here, we use electrochemical topotactic deintercalation to remove Pb from the centrosymmetric parent compound Au$_2$PbP$_2$, producing the polar metal Au$_2$Pb$_{0.914}$P$_2$. Unlike conventional chemical doping, this transformation actively drives structural symmetry-breaking: the partial removal of Pb triggers a cooperative electronic and geometric rearrangement, mediated by a second-order Jahn-Teller effect and stereochemically active lone pairs, that locks the product into a polar, noncentrosymmetric superspace group Ama2(01g)ss0. We solve the complete (3+1)D modulated structure by synchrotron single-crystal X-ray diffraction and confirm the polar assignment through nonlinear electronic transport. Below T$_c$ = 1.52 K, Au$_2$Pb$_{0.914}$P$_2$ becomes a type-II superconductor whose heat capacity and AC susceptibility both exhibit power-law behavior, suggestive of a gap structure governed by the broken inversion symmetry of the host lattice. This work establishes electrochemical oxidation as a rational route to metastable noncentrosymmetric superconductors through chemically directed symmetry-breaking.
PARADIM Data Collective · 2026-04-20
otherOpen accessSenior authorArXiv.org · 2026-05-15
articleOpen accessSenior authorIncorporation of $\mathrm{Al_{y}Ga_{1-y}N}$ (AGN) semiconductors into high power electronics offers efficiency improvements in power transmission, generation, and use, if approaches to eliminate the defects arising from film-lattice mismatch can be established. Here, we report the optical floating zone crystal growth of $\mathrm{Ta_{1-x}Hf_{x}C_{0.5}}$ (x = 0.2), a new metallic substrate material family lattice matched to the ultra-wide-band-gap, Al-rich side (y = 0.91) of the AGN solid solution. Laue diffraction demonstrates large single crystal domains in the as-grown boule. Single crystal x-ray diffraction at T = 213 K in conjunction with first principles calculations shows that the material adopts a layered crystal structure with AA-type stacking of (Ta/Hf)-C-(Ta/Hf) trilayers described in the trigonal space group P-3m1 (#164), with a = 3.1168(4) Å, c = 4.9644(4) Å, and $β$ = 120.0°. X-ray photoelectron spectroscopy (XPS) measurements show the Hf:Ta ratio to be close to the nominal value of 0.8:0.2 in the grown crystal. Density Functional Theory calculations reveal that this structure is stabilized by the low energy of carbon-vacancy formation of a hypothetical $\mathrm{(Ta/Hf)_{1}C_{1}}$ anti-NiAs structure type, and imply flexibility in interface structure with an overlayer nitride film. A surface preparation/polishing procedure is developed that reduces root mean square (RMS) surface roughness from as-cut 130 nm to 7 nm as measured by atomic force microscopy. Scanning electron microscopy shows the presence of a native surface oxide, removed by polishing, along with carbon-rich pits. Time-domain thermoreflectance measurements show a room temperature thermal conductivity of $κ$ = 18.1(4) W m-1 K-1. These results provide key first steps for utilizing metallic, lattice matched, substrates for the growth of Al-rich AGN semiconductors.
arXiv (Cornell University) · 2026-05-15
preprintOpen accessSenior authorIncorporation of $\mathrm{Al_{y}Ga_{1-y}N}$ (AGN) semiconductors into high power electronics offers efficiency improvements in power transmission, generation, and use, if approaches to eliminate the defects arising from film-lattice mismatch can be established. Here, we report the optical floating zone crystal growth of $\mathrm{Ta_{1-x}Hf_{x}C_{0.5}}$ (x = 0.2), a new metallic substrate material family lattice matched to the ultra-wide-band-gap, Al-rich side (y = 0.91) of the AGN solid solution. Laue diffraction demonstrates large single crystal domains in the as-grown boule. Single crystal x-ray diffraction at T = 213 K in conjunction with first principles calculations shows that the material adopts a layered crystal structure with AA-type stacking of (Ta/Hf)-C-(Ta/Hf) trilayers described in the trigonal space group P-3m1 (#164), with a = 3.1168(4) Å, c = 4.9644(4) Å, and $β$ = 120.0°. X-ray photoelectron spectroscopy (XPS) measurements show the Hf:Ta ratio to be close to the nominal value of 0.8:0.2 in the grown crystal. Density Functional Theory calculations reveal that this structure is stabilized by the low energy of carbon-vacancy formation of a hypothetical $\mathrm{(Ta/Hf)_{1}C_{1}}$ anti-NiAs structure type, and imply flexibility in interface structure with an overlayer nitride film. A surface preparation/polishing procedure is developed that reduces root mean square (RMS) surface roughness from as-cut 130 nm to 7 nm as measured by atomic force microscopy. Scanning electron microscopy shows the presence of a native surface oxide, removed by polishing, along with carbon-rich pits. Time-domain thermoreflectance measurements show a room temperature thermal conductivity of $κ$ = 18.1(4) W m-1 K-1. These results provide key first steps for utilizing metallic, lattice matched, substrates for the growth of Al-rich AGN semiconductors.
Physical Review Letters · 2025-11-14 · 1 citations
articleCommon belief is that the large band shifts observed in incommensurate misfit compounds, e.g., (LaSe)_{1.14}(NbSe_{2})_{2}, are due to interlayer charge transfer. By contrast, our analysis, based on both angle-resolved photoemission spectroscopy (ARPES) measurements and a specialized ab initio framework employing only quantities well defined in incommensurate materials, demonstrates that the large band shifts instead reflect changes in valence band hybridization and interlayer bonding. The strong alignment of our ab initio predictions and ARPES measurements confirms our understanding of the incommensurate electronic structure and charge transfer.
Compensation doping of the qubit host Ba2CaWO6-δ
Materials Today Quantum · 2025-02-19
articleOpen accessSenior authorCorrespondingEmerging quantum information science (QIS) technologies require advances in controlling the type, number, and distribution of defects in complex crystalline matter. Building on recent reports of promising spin-lattice relaxation times in oxygen-vacancy-induced W 5+ centers in the double perovskite Ba 2 CaWO 6-δ , here we report on the viability of compensation doping with Zr 4+ and Ge 4+ to tune the number of active W 5+ centers, a pre-requisite for mitigating spin bath effects and increasing spin-spin relaxation times. We prepared single crystals of nominal composition Ba 2 CaW 1-x M x O 6-δ (M = Zr 4+ , Ge 4+ ) for x = 0–0.20. Electron paramagnetic resonance (EPR) and DC magnetic susceptibility measurements were used to understand the changes in spin-active defects as a function of substitution. We find that x = 0.01 (M = Zr 4+ ) and x = 0.03 (M = Ge 4+ ) are sufficient to quench the W 5+ S = ½ EPR response (g = 2.00) within our limit of detection. Further substitution results in the appearance of a narrow S = ½ response (g = 1.98–2.00) that fades away at higher compositions. We conclude that compensation doping is an effective strategy for modulation of single ion centers in Ba 2 CaWO 6-δ and identify future steps that are needed to bring such complex materials to viability for QIS technologies, including proposal of an easily measured figure of merit for rapid materials iteration and optimization. • Inclusion of Zr 4+ or Ge 4+ modulates qubit density in Ba2CaWO 6-δ. • Laser diode floating zone growth produces large single crystal boules. • Variety of crystalline colors demonstrates complex defect reactions.
Recent grants
Frequent coauthors
- 91 shared
Juan R. Chamorro
Johns Hopkins University
- 79 shared
C. Broholm
Johns Hopkins University
- 68 shared
W. Adam Phelan
- 60 shared
R. J. Cava
- 53 shared
S. M. Koohpayeh
Johns Hopkins University
- 46 shared
Benjamin A. Trump
NIST Center for Neutron Research
- 43 shared
T. Thao Tran
Clemson University
- 42 shared
John P. Sheckelton
Labs
Quantum Materials Research Group
- Resume-aware match score
- Save to shortlist
- AI-drafted outreach
See your match with Tyrel M. McQueen
PhdFit ranks faculty by your research interests, methods, and publications — grounded in their actual work, not templates.
- Free to start
- No credit card
- 30-second signup