Dr. Christopher T. Parzyck

All Publications

• Growth of tetragonal PtO by molecular-beam epitaxy and its integration into β-Ga₂O₃ Schottky diodes APL MATERIALS Hensling, F. V. E., Parzyck, C. T., Cromer, B., Al Mamun, M., Suyolcu, Y., Kalaydjian, L., Subedi, I., Park, J., Azizie, K., Song, Q., Van Aken, P. A., Podraza, N. J., Cho, K., Jena, D., Xing, H. G., Shen, K. M., Schlom, D. G., Vogt, P. 2025; 13 (11)

  View details for DOI 10.1063/5.0274229

  View details for Web of Science ID 001616141700001

• Anisotropic spin stripe domains in bilayer La₃Ni₂O₇ NATURE COMMUNICATIONS Gupta, N. K., Gong, R., Wu, Y., Kang, M., Parzyck, C. T., Gregory, B. Z., Costa, N., Sutarto, R., Sarker, S., Singer, A., Schlom, D. G., Shen, K. M., Hawthorn, D. G. 2025; 16 (1)

  View details for DOI 10.1038/s41467-025-61653-w

  View details for Web of Science ID 001530788700030

  View details for PubMedID 40670364

• Superconductivity in the Parent Infinite-Layer Nickelate NdNiO2 PHYSICAL REVIEW X Parzyck, C. T., Wu, Y., Bhatt, L., Kang, M., Arthur, Z., Pedersen, T. M., Sutarto, R., Fan, S., Pelliciari, J., Bisogni, V., Herranz, G., Georgescu, A. B., Hawthorn, D. G., Kourkoutis, L. F., Muller, D. A., Schlom, D. G., Shen, K. M. 2025; 15 (2)

  View details for DOI 10.1103/PhysRevX.15.021048

  View details for Web of Science ID 001493067700002

• Is Ba₃In₂O₆ a high-<i>T_c </i> superconductor? JOURNAL OF PHYSICS-CONDENSED MATTER Hensling, F. E., Dahliah, D., Smeaton, M. A., Shrestha, B., Show, Parzyck, C. T., Hennighausen, C., Kotsonis, G. N., Rignanese, G., Barone, M. R., Subedi, Disa, A. S., Shen, K. M., Faeth, B. D., Bollinger, A. T., Bozovic, Podraza, N. J., Kourkoutis, L. F., Hautier, G., Schlom, D. G. 2024; 36 (31)

  Abstract

  It has been suggested that Ba3In2O6might be a high-Tcsuperconductor. Experimental investigation of the properties of Ba3In2O6was long inhibited by its instability in air. Recently epitaxial Ba3In2O6with a protective capping layer was demonstrated, which finally allows its electronic characterization. The optical bandgap of Ba3In2O6is determined to be 2.99 eV in-the (001) plane and 2.83 eV along thec-axis direction by spectroscopic ellipsometry. First-principles calculations were carried out, yielding a result in good agreement with the experimental value. Various dopants were explored to induce (super-)conductivity in this otherwise insulating material. NeitherA- norB-site doping proved successful. The underlying reason is predominately the formation of oxygen interstitials as revealed by scanning transmission electron microscopy and first-principles calculations. Additional efforts to induce superconductivity were investigated, including surface alkali doping, optical pumping, and hydrogen reduction. To probe liquid-ion gating, Ba3In2O6was successfully grown epitaxially on an epitaxial SrRuO3bottom electrode. So far none of these efforts induced superconductivity in Ba3In2O6,leaving the answer to the initial question of whether Ba3In2O6is a high-Tcsuperconductor to be 'no' thus far.

  View details for DOI 10.1088/1361-648X/ad42f3

  View details for Web of Science ID 001219447200001

  View details for PubMedID 38657622

• Surface reconstructions and electronic structure of metallic delafossite thin films APL MATERIALS Song, Q., He, Z., Faeth, B. D., Parzyck, C. T., Scheid, A., Mowers, C. J., Feng, Y., Xu, Q., Hasko, S., Park, J., Barone, M. R., Suyolcu, Y., van Aken, P. A., Pamuk, B., Fennie, C. J., King, P. D. C., Shen, K. M., Schlom, D. G. 2024; 12 (8)

  View details for DOI 10.1063/5.0217540

  View details for Web of Science ID 001291956900004

• Synthesis of thin film infinite-layer nickelates by atomic hydrogen reduction: Clarifying the role of the capping layer APL MATERIALS Parzyck, C. T., Anil, V., Wu, Y., Goodge, B. H., Roddy, M., Kourkoutis, L. F., Schlom, D. G., Shen, K. M. 2024; 12 (3)

  View details for DOI 10.1063/5.0197304

  View details for Web of Science ID 001190267700004

• Absence of 3<i>a</i>₀ charge density wave order in the infinite-layer nickelate NdNiO₂( Jan , 2024 , 10.1038/s41563-024-01797-0) NATURE MATERIALS Parzyck, C. T., Gupta, N. K., Wu, Y., Anil, V., Bhatt, L., Bouliane, M., Gong, R., Gregory, B. Z., Luo, A., Sutarto, R., He, F., Chuang, Y., Zhou, T., Herranz, G., Kourkoutis, L. F., Singer, A., Schlom, D. G., Hawthorn, D. G., Shen, K. M. 2024; 23 (3): 440

  View details for DOI 10.1038/s41563-024-01832-0

  View details for Web of Science ID 001180729500023

  View details for PubMedID 38347120

  View details for PubMedCentralID PMC10917676

• Absence of 3<i>a</i>₀ charge density wave order in the infinite-layer nickelate NdNiO₂ NATURE MATERIALS Parzyck, C. T., Gupta, N. K., Wu, Y., Anil, V., Bhatt, L., Bouliane, M., Gong, R., Gregory, B. Z., Luo, A., Sutarto, R., He, F., Chuang, Y., Zhou, T., Herranz, G., Kourkoutis, L. F., Singer, A., Schlom, D. G., Hawthorn, D. G., Shen, K. M. 2024; 23 (4): 486-491

  Abstract

  A hallmark of many unconventional superconductors is the presence of many-body interactions that give rise to broken-symmetry states intertwined with superconductivity. Recent resonant soft X-ray scattering experiments report commensurate 3a0 charge density wave order in infinite-layer nickelates, which has important implications regarding the universal interplay between charge order and superconductivity in both cuprates and nickelates. Here we present X-ray scattering and spectroscopy measurements on a series of NdNiO2+x samples, which reveal that the signatures of charge density wave order are absent in fully reduced, single-phase NdNiO2. The 3a0 superlattice peak instead originates from a partially reduced impurity phase where excess apical oxygens form ordered rows with three-unit-cell periodicity. The absence of any observable charge density wave order in NdNiO2 highlights a crucial difference between the phase diagrams of cuprate and nickelate superconductors.

  View details for DOI 10.1038/s41563-024-01797-0

  View details for Web of Science ID 001152202500001

  View details for PubMedID 38278983

  View details for PubMedCentralID PMC10990928

• Atomically smooth films of CsSb: A chemically robust visible light photocathode APL MATERIALS Parzyck, C. T., Pennington, C. A., DeBenedetti, W. I., Balajka, J., Echeverria, E. M., Paik, H., Moreschini, L., Faeth, B. D., Hu, C., Nangoi, J. K., Anil, V., Arias, T. A., Hines, M. A., Schlom, D. G., Galdi, A., Shen, K. M., Maxson, J. M. 2023; 11 (10)

  View details for DOI 10.1063/5.0166334

  View details for Web of Science ID 001100362100001

• Growth of PdCoO₂ films with controlled termination by molecular-beam epitaxy and determination of their electronic structure by angle-resolved photoemission spectroscopy APL MATERIALS Song, Q., Sun, J., Parzyck, C. T., Miao, L., Xu, Q., Hensling, F. V. E., Barone, M. R., Hu, C., Kim, J., Faeth, B. D., Paik, H., King, P. D. C., Shen, K. M. M., Schlom, D. G. 2022; 10 (9)

  View details for DOI 10.1063/5.0101837

  View details for Web of Science ID 000876206200002

• Canonical approach to cation flux calibration in oxide molecular-beam epitaxy PHYSICAL REVIEW MATERIALS Sun, J., Parzyck, C. T., Lee, J. H., Brooks, C. M., Kourkoutis, L. F., Ke, X., Misra, R., Schubert, J., Hensling, F., Barone, M. R., Wang, Z., Holtz, M. E., Schreiber, N. J., Song, Q., Paik, H., Heeg, T., Muller, D. A., Shen, K. M., Schlom, D. G. 2022; 6 (3)

  View details for DOI 10.1103/PhysRevMaterials.6.033802

  View details for Web of Science ID 000779822600003

• Single-Crystal Alkali Antimonide Photocathodes: High Efficiency in the Ultrathin Limit PHYSICAL REVIEW LETTERS Parzyck, C. T., Galdi, A., Nangoi, J. K., DeBenedetti, W. J., Balajka, J., Faeth, B. D., Paik, H., Hu, C., Arias, T. A., Hines, M. A., Schlom, D. G., Shen, K. M., Maxson, J. M. 2022; 128 (11): 114801

  Abstract

  The properties of photoemission electron sources determine the ultimate performance of a wide class of electron accelerators and photon detectors. To date, all high-efficiency visible-light photocathode materials are either polycrystalline or exhibit intrinsic surface disorder, both of which limit emitted electron beam brightness. In this Letter, we demonstrate the synthesis of epitaxial thin films of Cs_{3}Sb on 3C-SiC (001) using molecular-beam epitaxy. Films as thin as 4 nm have quantum efficiencies exceeding 2% at 532 nm. We also find that epitaxial films have an order of magnitude larger quantum efficiency at 650 nm than comparable polycrystalline films on Si. Additionally, these films permit angle-resolved photoemission spectroscopy measurements of the electronic structure, which are found to be in good agreement with theory. Epitaxial films open the door to dramatic brightness enhancements via increased efficiency near threshold, reduced surface disorder, and the possibility of engineering new photoemission functionality at the level of single atomic layers.

  View details for DOI 10.1103/PhysRevLett.128.114801

  View details for Web of Science ID 000782905600002

  View details for PubMedID 35363005

• Strong interlayer interactions in bilayer and trilayer moire superlattices SCIENCE ADVANCES Xie, S., Faeth, B. D., Tang, Y., Li, L., Gerber, E., Parzyck, C. T., Chowdhury, D., Zhang, Y., Jozwiak, C., Bostwick, A., Rotenberg, E., Kim, E., Shan, J., Mak, K., Shen, K. M. 2022; 8 (12): eabk1911

  Abstract

  Moiré superlattices constructed from transition metal dichalcogenides have demonstrated a series of emergent phenomena, including moiré excitons, flat bands, and correlated insulating states. All of these phenomena depend crucially on the presence of strong moiré potentials, yet the properties of these moiré potentials, and the mechanisms by which they can be generated, remain largely open questions. Here, we use angle-resolved photoemission spectroscopy with submicron spatial resolution to investigate an aligned WS2/WSe2 moiré superlattice and graphene/WS2/WSe2 trilayer heterostructure. Our experiments reveal that the hybridization between moiré bands in WS2/WSe2 exhibits an unusually large momentum dependence, with the splitting between moiré bands at the Γ point more than an order of magnitude larger than that at K point. In addition, we discover that the same WS2/WSe2 superlattice can imprint an unexpectedly large moiré potential on a third, separate layer of graphene (g/WS2/WSe2), suggesting new avenues for engineering two-dimensional moiré superlattices.

  View details for DOI 10.1126/sciadv.abk1911

  View details for Web of Science ID 000800334900006

  View details for PubMedID 35333575

  View details for PubMedCentralID PMC8956267

• Interfacial charge transfer and persistent metallicity of ultrathin SrIrO₃/SrRuO₃ heterostructures SCIENCE ADVANCES Nelson, J. N., Schreiber, N. J., Georgescu, A. B., Goodge, B. H., Faeth, B. D., Parzyck, C. T., Zeledon, C., Kourkoutis, L. F., Millis, A. J., Georges, A., Schlom, D. G., Shen, K. M. 2022; 8 (5): eabj0481

  Abstract

  Interface quantum materials have yielded a plethora of previously unknown phenomena, including unconventional superconductivity, topological phases, and possible Majorana fermions. Typically, such states are detected at the interface between two insulating constituents by electrical transport, but whether either material is conducting, transport techniques become insensitive to interfacial properties. To overcome these limitations, we use angle-resolved photoemission spectroscopy and molecular beam epitaxy to reveal the electronic structure, charge transfer, doping profile, and carrier effective masses in a layer-by-layer fashion for the interface between the Dirac nodal-line semimetal SrIrO3 and the correlated metallic Weyl ferromagnet SrRuO3. We find that electrons are transferred from the SrIrO3 to SrRuO3, with an estimated screening length of λ = 3.2 ± 0.1 Å. In addition, we find that metallicity is preserved even down to a single SrIrO3 layer, where the dimensionality-driven metal-insulator transition typically observed in SrIrO3 is avoided because of strong hybridization of the Ir and Ru t2g states.

  View details for DOI 10.1126/sciadv.abj0481

  View details for Web of Science ID 000799992000003

  View details for PubMedID 35119924

  View details for PubMedCentralID PMC8816341

• Computational synthesis of substrates by crystal cleavage NPJ COMPUTATIONAL MATERIALS Paul, J. T., Galdi, A., Parzyck, C., Shen, K. M., Maxson, J., Hennig, R. G. 2021; 7 (1)

  View details for DOI 10.1038/s41524-021-00608-3

  View details for Web of Science ID 000695822800001

• Interfacial Electron-Phonon Coupling Constants Extracted from Intrinsic Replica Bands in Monolayer FeSe/SrTiO₃ PHYSICAL REVIEW LETTERS Faeth, B. D., Xie, S., Yang, S., Kawasaki, J. K., Nelson, J. N., Zhang, S., Parzyck, C., Mishra, P., Li, C., Jozwiak, C., Bostwick, A., Rotenberg, E., Schlom, D. G., Shen, K. M. 2021; 127 (1): 016803

  Abstract

  The observation of replica bands by angle-resolved photoemission spectroscopy has ignited interest in the study of electron-phonon coupling at low carrier densities, particularly in monolayer FeSe/SrTiO_{3}, where the appearance of replica bands has motivated theoretical work suggesting that the interfacial coupling of electrons in the FeSe layer to optical phonons in the SrTiO_{3} substrate might contribute to the enhanced superconducting pairing temperature. Alternatively, it has also been recently proposed that such replica bands might instead originate from extrinsic final state losses associated with the photoemission process. Here, we perform a quantitative examination of replica bands in monolayer FeSe/SrTiO_{3}, where we are able to conclusively demonstrate that the replica bands are indeed signatures of intrinsic electron-boson coupling, and not associated with final state effects. A detailed analysis of the energy splittings and relative peak intensities between the higher-order replicas, as well as other self-energy effects, allows us to determine that the interfacial electron-phonon coupling in the system corresponds to a value of λ=0.19±0.02, providing valuable insights into the enhancement of superconductivity in monolayer FeSe/SrTiO_{3}. The methodology employed here can also serve as a new and general approach for making more rigorous and quantitative comparisons to theoretical calculations of electron-phonon interactions and coupling constants.

  View details for DOI 10.1103/PhysRevLett.127.016803

  View details for Web of Science ID 000669052600007

  View details for PubMedID 34270322

• Incoherent Cooper Pairing and Pseudogap Behavior in Single-Layer FeSe/SrTiO₃ PHYSICAL REVIEW X Faeth, B. D., Yang, S., Kawasaki, J. K., Nelson, J. N., Mishra, P., Parzyck, C. T., Li, C., Schlom, D. G., Shen, K. M. 2021; 11 (2)

  View details for DOI 10.1103/PhysRevX.11.021054

  View details for Web of Science ID 000661891300001

• Mott gap collapse in lightly hole-doped Sr_2-<i>x</i>K_<i>x</i>IrO₄ NATURE COMMUNICATIONS Nelson, J. N., Parzyck, C. T., Faeth, B. D., Kawasaki, J. K., Schlom, D. G., Shen, K. M. 2020; 11 (1): 2597

  Abstract

  The evolution of Sr2IrO4 upon carrier doping has been a subject of intense interest, due to its similarities to the parent cuprates, yet the intrinsic behaviour of Sr2IrO4 upon hole doping remains enigmatic. Here, we synthesize and investigate hole-doped Sr2-xKxIrO4 utilizing a combination of reactive oxide molecular-beam epitaxy, substitutional diffusion and in-situ angle-resolved photoemission spectroscopy. Upon hole doping, we observe the formation of a coherent, two-band Fermi surface, consisting of both hole pockets centred at (π, 0) and electron pockets centred at (π/2, π/2). In particular, the strong similarities between the Fermi surface topology and quasiparticle band structure of hole- and electron-doped Sr2IrO4 are striking given the different internal structure of doped electrons versus holes.

  View details for DOI 10.1038/s41467-020-16425-z

  View details for Web of Science ID 000537135100018

  View details for PubMedID 32444617

  View details for PubMedCentralID PMC7244596

• Enhanced surface superconductivity in Ba(Fe_0.95Co_0.05)₂As₂ APPLIED PHYSICS LETTERS Parzyck, C. T., Faeth, B. D., Tam, G. N., Stewart, G. R., Shen, K. M. 2020; 116 (6)

  View details for DOI 10.1063/1.5133647

  View details for Web of Science ID 000525300100001

• Low energy photoemission from (100) Ba_1-xLa_xSnO₃ thin films for photocathode applications EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS Galdi, A., Pierce, C. M., Cultrera, L., Adhikari, G., Schroeder, W., Paik, H., Schlom, D. G., Nangoi, J. K., Arias, T. A., Lochocki, E., Parzyck, C., Shen, K. M., Maxson, J. M., Bazarov, I. V. 2019; 228 (3): 713-718

  View details for DOI 10.1140/epjst/e2019-800175-x

  View details for Web of Science ID 000473209200011

• Stress relaxation in quasi-two-dimensional self-assembled nanoparticle monolayers PHYSICAL REVIEW E Boucheron, L. S., Stanley, J. T., Dai, Y., You, S., Parzyck, C. T., Narayanan, S., Sandy, A. R., Jiang, Z., Meron, M., Lin, B., Shpyrko, O. G. 2018; 97 (5): 052803

  Abstract

  We experimentally probed the stress relaxation of a monolayer of iron oxide nanoparticles at the water-air interface. Upon drop-casting onto a water surface, the nanoparticles self-assembled into islands of two-dimensional hexagonally close packed crystalline domains surrounded by large voids. When compressed laterally, the voids gradually disappeared as the surface pressure increased. After the compression was stopped, the surface pressure (as measured by a Wilhelmy plate) evolved as a function of the film aging time with three distinct timescales. These aging dynamics were intrinsic to the stressed state built up during the non-equilibrium compression of the film. Utilizing x-ray photon correlation spectroscopy, we measured the characteristic relaxation time (τ) of in-plane nanoparticle motion as a function of the aging time through both second-order and two-time autocorrelation analysis. Compressed and stretched exponential fitting of the intermediate scattering function yielded exponents (β) indicating different relaxation mechanisms of the films under different compression stresses. For a monolayer compressed to a lower surface pressure (between 20 mN/m and 30 mN/m), the relaxation time (τ) decreased continuously as a function of the aging time, as did the fitted exponent, which transitioned from being compressed (>1) to stretched (<1), indicating that the monolayer underwent a stress release through crystalline domain reorganization. However, for a monolayer compressed to a higher surface pressure (around 40 mN/m), the relaxation time increased continuously and the compressed exponent varied very little from a value of 1.6, suggesting that the system may have been highly stressed and jammed. Despite the interesting stress relaxation signatures seen in these samples, the structural ordering of the monolayer remained the same over the sample lifetime, as revealed by grazing incidence x-ray diffraction.

  View details for DOI 10.1103/PhysRevE.97.052803

  View details for Web of Science ID 000432979800006

  View details for PubMedID 29906983

• Coarse spectral characterization of warm x-rays at the Z facility using a filtered thermoluminescent dosimeter array REVIEW OF SCIENTIFIC INSTRUMENTS Harper-Slaboszewicz, V. J., Ulmen, B. A., Parzyck, C. T., Ampleford, D. J., McCourt, A. L., Bell, K. S., Coverdale, C. A. 2017; 88 (4): 043501

  Abstract

  A new collimated filtered thermoluminescent dosimeter (TLD) array has been developed at the Z facility to characterize warm x-rays (hν > 10 keV) produced by Z pinch radiation sources. This array includes a Kapton debris shield assembly to protect the TLDs from the source debris, a collimator array to limit the field of view of the TLDs to the source region, a filter wheel containing filters of aluminum, copper and tungsten up to 3 mm thick to independently filter each TLD, and a hermetically sealed cassette containing the TLDs as well as tungsten shielding on the sides and back of the array to minimize scattered radiation reaching the TLDs. Experimental results from a krypton gas puff and silver wire array shot are analyzed using two different functional forms of the energy spectrum to demonstrate the ability of this diagnostic to consistently extend the upper end of the x-ray spectrum characterization from ∼50 keV to >1 MeV.

  View details for DOI 10.1063/1.4979626

  View details for Web of Science ID 000400392800014

  View details for PubMedID 28456222