Physics Commons^™

Glassy Magnetic Freezing Of Interacting Clusters In Materials Related To The Lk-99 Family, Serafim Teknowijoyo, Domenico Napoletani, Vahan Nikoghosyan, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

We report reproducible magnetization anomalies appearing below room temperature in copper-doped apatite materials belonging to the LK-99 family synthesized via hydrothermal methods. These anomalies are observed consistently across samples prepared under comparable conditions. Although the extracted Mydosh parameter lies within the range often associated with vortex-glass behavior in superconductors, a detailed analysis of DC magnetization, AC susceptibility, field dependence, and magnetic memory effects demonstrates that the observed phenomena are not related to superconductivity. Instead, the data are consistent with glassy magnetic freezing of interacting clusters. Compositional and structural analysis identifies covellite (CuS), one of the constituent phases in these multiphase …

Electronic Transport In Twisted Bilayer Tungsten Diselenides, Walid Zaher

Theses and Dissertations

This thesis investigates density waves (DWs) in twisted bilayer tungsten diselenide (tWSe₂) using a mean field approximation, with a focus on electron-electron interactions, and the system’s free energy at zero temperature. For the mean field approximation, the study initially employed same-spin nesting vectors, which were found insufficient to induce DWs formation. In contrast, when opposite-spin nesting vectors were used, DWs emerged, indicating that these vectors can support DWs formation. The plots were produced under perfect nesting conditions, where van Hove singularities (VHS) occur. At zero temperature, perfect nesting provides a complete picture of the upper limit of DWs formation, as …

A Stability Analysis Of The Phase-Lock Equations, Brian M. Sunguza

UNF Graduate Theses and Dissertations

Ginzburg and Landau have provided a set of equations that relate superconductivity to magnetic fields. Through a transformation process, Zhan has derived what are now called the phase-lock equations. A stability analysis of the spatially-independent phase-lock equations is the purpose of this presentation. This simplification is significant since it allowed for the analytical determination of equilibria, their stability, and the influence of a periodic forcing function. Through the use of an original code, numerical simulations are shown to corroborate the analytical results described above.

This analysis includes novel Lyapunov functions that allowed for the analytical determination of the instability region. …

First Principles Calculation Of Electron-Phonon Coupling In Nonequilibrium Quantum Materials, Chendi Xie

All Dissertations

This dissertation combines first-principles computation and light-induced nonequilibrium analysis to understand and control electron–phonon coupling (EPC) and emergent many-body phenomena in quantum materials, in both equilibrium and nonequilibrium states.

Chapters 1 and 2 build the theoretical and computational foundation, beginning with electron and phonon self-energies, linewidths, and perturbation theory for EPC, followed by density functional theory (DFT) and density functional perturbation theory (DFPT), which serve as the first-principles workhorses used throughout. Chapter 3 reviews Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg theory, including the BCS gap - transition temperature (T_c) relation and the strong-coupling generalization, and delineates the practical validity bound …

Gate-Controlled Supercurrent Effect In Dry-Etched Dayem Bridges Of Non-Centrosymmetric Niobium Rhenium, Jennifer Koch, Carla Cirillo, Sebastiano Battisti, Leon Ruf, Zahra Makhdoumi Kakhaki, Alessandro Paghi, Armen Gulian, Serafim Teknowijoyo, Giorgio De Simoni, Francesco Giazotto, Carmine Attanasio, Elke Scheer, Angelo Di Bernardo

Mathematics, Physics, and Computer Science Faculty Articles and Research

The application of a gate voltage to control the superconducting current flowing through a nanoscale superconducting constriction, named as gate-controlled supercurrent (GCS), has raised great interest for fundamental and technological reasons. To gain a deeper understanding of this effect and develop superconducting technologies based on it, the material and physical parameters crucial for the GCS effect must be identified. Top-down fabrication protocols should also be optimized to increase device scalability, although studies suggest that top-down fabricated devices are more resilient to show a GCS. Here, we investigate gated superconducting nanobridges made with a top-down fabrication process from thin films of …

Direct Measurement Of Microwave Loss In Nb Films For Superconducting Qubits, B. Abdisatarov, D. Bafia, A. Murthy, G. Eremeev, H. E. Elsayed-Ali, J. Lee, A. Netepenko, C. P. A. Carlos, S. Leith, G. J. Rosaz, A. Romanenko, A. Grassellino

Electrical & Computer Engineering Faculty Publications

Niobium films are a key component in modern two-dimensional superconducting qubits, yet their contribution to the total qubit decay rate is not fully understood. The presence of different layers of materials and interfaces makes it difficult to identify the dominant loss channels in present two-dimensional qubit designs. In this paper, we present the study that directly correlates measurements of RF losses in such films to material parameters by investigating a high-power impulse magnetron sputtered (HiPIMS) film atop a three-dimensional niobium superconducting radio frequency (SRF) resonator. By using a 3D SRF structure, we are able to isolate the niobium film loss …

Investigation Of Hot-Spots Due To Trapped Flux In Niobium Superconducting Radiofrequency Cavities, B. Khanal, P. Dhakal

Physics Faculty Publications

One of the significant sources of residual losses in superconducting radio-frequency cavities is magnetic flux trapped during the cool-down due to the incomplete Messier effect. If the trapped vortices are non-uniformly distributed on the cavity surface, the temperature mapping revealed the “hot-spots” at the location of high density of pinned vortices. Here, we performed a rf test on 1.3 GHz single cell cavity with the combination of the temperature mapping system. The temperature mapping reveled the development of the hot spots with the increase in rf field inside the cavity. When magnetic field is trapped locally on the surface of …

Design And Performance Of Superconducting Switches For Nanowire Detectors In Magnetic Fields, Timothy James Draher

Graduate Research Theses & Dissertations

Superconducting nanowire devices fit a broad spectrum of applications, including particle detection and quantum computing, and their expanding use across various fields highlights their role in the hybridization of superconducting and conventional semiconductor electronics. Despite their potential, the low signal output of these devices raises challenges in scalability and integration, particularly in applications for nuclear and high-energy physics, where resilience in magnetic fields is becoming a critical optimization factor. The superconducting nanowire cryotron (nTron) addresses these issues by providing operational gain and logic switching in superconducting nanowire circuits, demonstrating adaptability to multiple materials. This dissertation focuses on modifying the conventional …

Computational Modeling Of Superconductivity From The Set Of Time-Dependent Ginzburg-Landau Equations For Advancements In Theory And Applications, Iris Mowgood

Computational and Data Sciences (PhD) Dissertations

A full review of the research conducted and published during my PhD studies in Computational and Data Sciences at Chapman University, under the advisement of Dr. Armen Gulian, are presented. Using the set of time-dependent Ginzburg-Landau (TDGL) equations with inclusion of the interference current and the non-equilibrium phonon term, we modeled the dynamics of superconductors in various theory revealing states and practical purposes. A review of the history and phenomenon of superconductivity, including modern applications, is introduced. The Josephson effect and associated Josephson junction are discussed for comparison to our analogous results with the 1-D superconducting wire. The mathematics of …

Nb3Sn Coating Of Twin Axis Cavity And Other Complex Srf Cavity Structures, Jayendrika Kumari Tiskumara

Physics Theses & Dissertations

In the field of Accelerator Science, for the low cost and increased quality factor, thin films coated niobium cavities are used in the modern SRF research. Within the potential substances, Nb₃Sn has shown higher critical temperature than niobium. Here the tin vapor diffusion method is used as the preferred technique to coat niobium cavities. So far, only elliptical cavities have been coated with Nb₃Sn and this technique has not yet been applied to cavities with complex geometries, which are also helpful in the accelerator science field. The Half-wave resonator could provide us data across frequencies of …

Stoichiometric Determination Of Hydride Materials At Extreme Conditions, Gregory Alexander Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen was predicted to be a high-temperature superconductor at near-megabar conditions in 1968,[1] but only recently was been experimentally observed.[2] This is due to the extraneous metrological constraint of requiring 5 megabars of pressure to stabilize. A more practical approach for synthesis of high-temperature superconductors has been pro-posed through the use of hydride compounds. Recently, a surge of rare earth hydrides have achieved critical superconducting transition temperatures (T_C ) close to room temperature.[3, 4, 5, 6] However, due to limitations of the necessary instrumentation to achieve megabar pressures, many techniques traditionally used to measure stoichiometry are unavailable.Three works presented in …

High-Frequency Diode Effect In Superconducting Nb3Sn Microbridges, Sara Chahid, Serafim Teknowijoyo, Iris Mowgood, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

The superconducting diode effect has recently been reported in a variety of systems and different symmetry-breaking mechanisms have been examined. However, the frequency range of these potentially important devices still remains obscure. We investigated superconducting microbridges of Nb3Sn in out-of-plane magnetic fields; optimum magnetic fields of ∼10 mT generate ∼10% diode efficiency, while higher fields of ∼15–20 mT quench the effect. The diode changes its polarity with magnetic field reversal. We documented superconductive diode rectification at frequencies up to 100 kHz, the highest reported as of today. Interestingly, the bridge resistance during diode operation reaches a value that is a …

Thin Film Deposition Of Mop, A Topological Semimetal, Robert Browning, Paul Plachinda, Raj Solanki

Physics Faculty Publications and Presentations

MoP is a topological semimetal which has drawn attention due to its unique electrical and optical properties resulting from massless electrons. In order to utilize these properties for practical applications, it is necessary to develop a technique to produce high-quality, large-scale thin films of this 2D material. We report below our initial results of growth of MoP thin films using atomic layer deposition (ALD), where the film grows layer-by-layer. These films were grown on 5 cm × 5 cm silicon oxide coated Si wafers. Resistivity versus temperature measurements show that these films are metallic and includes a partial superconducting phase. …

Numerical Calculations Of Superheating Field In Superconductors With Nanostructured Surfaces, M.R.P. Walive Pathiranage, A. Gurevich

Physics Faculty Publications

We re­port cal­cu­la­tions of a dc su­per­heat­ing field Hs in su­per­con­duc­tors with nanos­truc­tured sur­faces. Par­tic­u­larly, we per­formed nu­mer­i­cal sim­u­la­tions of the Ginzburg-Lan­dau (GL) equa­tions for a su­per­con­duc­tor with an in­ho­mo­ge­neous pro­file of im­pu­rity con­cen­tra­tion, a thin su­per­con­duct­ing layer on top of an­other su­per­con­duc­tor, and S-I-S mul­ti­lay­ers. The su­per­heat­ing field was cal­cu­lated tak­ing into ac­count the in­sta­bil­ity of the Meiss­ner state at a fi­nite wave­length along the sur­face de­pend­ing on the value of the GL pa­ra­me­ter. Sim­u­la­tions were done for the ma­te­ri­als pa­ra­me­ters of Nb and Nb₃Sn at dif­fer­ent val­ues of the GL pa­ra­me­ter and the mean free paths. We show …

Development Of A Prototype Superconducting Radio-Frequency Cavity For Conduction Cooled Accelerators, Gianluigi Ciovati, J. Anderson, S. Balachandran, G. Cheng, B. Coritron, E. Daly, P. Dhakal, Alex Gurevich, F. Hannon, K. Harding, L. Holland, F. Marhauser, K. Mclaughlin, D. Packard, T. Powers, U. Pudasaini, J. Rathke, R. Rimmer, T. Schultheiss, H. Vennekate, D. Vollmer

Physics Faculty Publications

The higher efficiency of superconducting radio-frequency (SRF) cavities compared to normal -conducting ones enables the development of high-energy continuous-wave linear accelerators (linacs). Recent progress in the development of high-quality Nb₃Sn film coatings along with the availability of cryocoolers with high cooling capacity at 4 K makes it feasible to operate SRF cavities cooled by thermal conduction at relevant accelerating gradients for use in accelerators. A possible use of conduction-cooled SRF linacs is for environmental applications, requiring electron beams with energy of 1-10 MeV and 1 MW of power. We have designed a 915 MHz SRF linac for such …

Characterization Of Dissipative Regions Of A N-Doped Superconducting Radio-Frequency Cavity, Eric M. Lechner, Basu Dev Oli, Junki Makita, Gianluigi Ciovati, Alex Gurevich, Maria Lavarone

Physics Faculty Publications

We report radio-frequency measurements of quality factors and temperature mapping of a nitrogen doped Nb superconducting RF cavity. Cavity cutouts of hot and cold spots were studied with low temperature scanning tunneling microscopy and spectroscopy, X-ray photoelectron spectroscopy and secondary electron microscopy. Temperature mapping revealed a substantial reduction of the residual resistance upon cooling the cavity with a greater temperature gradient and hysteretic losses at the quench location, pointing to trapped vortices as the dominant source of residual surface resistance.Analysis of the tunneling spectra in the framework of a proximity effect theory shows that hot spots have a reduced pair …

A Database For Crystalline Organic Conductors And Superconductors, Owen Ganter, Kevin Feeny, Morgan Brooke-Debock, Stephen M. Winter, Charles C. Agosta

Physics

We present a prototype database for quasi two-dimensional crystalline organic conductors and superconductors based on molecules related to bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF, ET). The database includes crystal structures, calculated electronic structures, and experimentally measured properties such as the superconducting transition temperature and critical magnetic fields. We obtained crystal structures from the Cambridge Structural Database and created a crystal structure analysis algorithm to identify cation molecules and execute tight binding electronic structure calculations. We used manual data entry to encode experimentally measured properties reported in publications. Crystalline organic conductors and superconductors exhibit a wide variety of electronic ground states, particularly those with correlations. …

Direct Current Magnetic Hall Probe Technique For Measurement Of Field Penetration In Thin Film Superconductors For Superconducting Radio Frequency Resonators, Iresha Harshani Senevirathne, Alex Gurevich, Jean Delayen

Physics Faculty Publications

Superconducting Radio Frequency (SRF) cavities used in particle accelerators are typically formed from or coated with superconducting materials. Currently, high purity niobium is the material of choice for SRF cavities that have been optimized to operate near their theoretical field limits. This brings about the need for significant R & D efforts to develop next generation superconducting materials that could outperform Nb and keep up with the demands of new accelerator facilities. To achieve high quality factors and accelerating gradients, the cavity material should be able to remain in the superconducting Meissner state under a high RF magnetic field without …

Lower Temperature Annealing Of Vapor Diffused Nb3Sn For Accelerator Cavities, Jayendrika K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini

Physics Faculty Publications

Nb₃Sn is a next-generation superconducting material for the accelerator cavities with higher critical temperature and superheating field, both twice compared to Nb. It promises superior performance and higher operating temperature than Nb, resulting in significant cost reduction. So far, the Sn vapor diffusion method is the most preferred and successful technique to coat niobium cavities with Nb₃Sn. Although several post-coating techniques (chemical, electrochemical, mechanical) have been explored to improve the surface quality of the coated surface, an effective process has yet to be found. Since there are only a few studies on the post-coating heat treatment …

Moiré-Driven Topological Transitions And Extremeanisotropy In Elastic Metasurfaces, Simon Yves, Matheus Inguaggiato Nora Nora Rosa, Mohit Gupta, Massimo Ruzzene, Andrea Alù

Advanced Science Research Center

The twist angle between a pair of stacked 2D materials has been recently shown to control remarkable phenomena, including the emergence of flat-band superconductivity in twisted graphene bilayers, of higher-order topological phases in twisted moiré superlattices, and of topological polaritons in twisted hyperbolic metasurfaces. These discoveries, at the foundations of the emergent field of twistronics, have so far been mostly limited to explorations in atomically thin condensed matter and photonic systems, with limitations on the degree of control over geometry and twist angle, and inherent challenges in the fabrication of carefully engineered stacked multilayers. Here, this work extends twistronics to …

Numerical Calculation Of Losses Of Trapped Vortices Under Strong Rf Meissner Current And Dc Superheating Field In Type Ii Superconductors, Walive Pathiranage Manula Randhika Pathirana

Physics Theses & Dissertations

Research on the vortex dynamics and enhancing of superheating field in superconductors has attracted much attention in accelerator physics community to develop next-generation high-performance accelerator cavities. However, the extreme dynamics of curvilinear elastic vortices driven by very strong currents close to the depairing limit or superheating field of a superconductor with a nanostructured surface has not been well understood. We calculated the superheating field H_sh and critical momentum kc characterizing the wavelength of the instability λ_m of the Meissner state to flux penetration by solving numerically the Ginzburg-Landau equations. A bulk superconductor, superconductor with the inhomogeneous surface disorder …

Novel Low Temperature Properties Of Filled And Unfilled Single Crystal Irsb3, Matthew Cook

Dissertations

The skutterudite family of materials has garnered a lot of attention in the condensed matter community and it persists to be an important system for exploring the fundamental physics of solids. The initial interest into compounds with this common structure was due to their promising thermoelectric properties giving the possibility of efficient energy harvesting. Since, there has been a huge effort to systematically synthesize new filled skutterudite compounds, as nearly every type of strongly correlated behavior has been found within this family. As the field of topological materials has gained momentum, these materials have also been given a renewed interest …

Nb3Sn Coating Of Complex Srf Cavity Structures, Jayendrika Tiskumara, Uttar Pudasaini, Grigory Eremeev, Charlie Reece, Jean Delayen

College of Sciences Posters

In the modern SRF research, Thin films coated niobium cavities are used for the low cost and increased quality factor. Among the potential thin film materials applied on the niobium, performances demonstrated by the Nb3Sn cavities makes this material attractive for SRF accelerator applications giving higher critical temperature and higher accelerating gradients. While the majority of research efforts are currently focused on the development of elliptical single-cell and multi-cell cavities, the potential of this material is evident to other cavity types, which may have complex geometries. We are working towards the development of Nb₃Sn-coated Half-wave resonator and twin …

The Magnetic Field Penetration Measurement Of Thin Film And Multilayered Superconductors For Srf Cavities, Iresha Harshani Senevirathne, Jean Delayen

College of Sciences Posters

Radio Frequency (RF) Cavities are used in particle accelerators and they are typically formed from or coated with superconducting materials. High purity niobium is the material of choice for SRF cavities and niobium cavities operate at their theoretical field limits. SRF researchers have begun a significant R&D effort to develop alternative materials to continue to keep up with the demands of new accelerator facilities. To achieve high performance with high accelerating gradient, cavity material should have an ability to persist in superconducting state under high magnetic field without magnetic flux penetration through the cavity wall. Therefore, the magnetic field at …

Majorana Quasiparticles In Topological Material Interfaces, David Alspaugh

LSU Doctoral Dissertations

In this dissertation we analyze how Majorana quasiparticles found on material interfaces of both topological insulators (TIs) and topological superconductors (TSCs) are affected by imperfections within their local environment. While these quasiparticles are predicted to be critical for the construction of quantum computers, they are typically modeled only under pristine conditions. Thus, although quantum computers may require the spatial manipulation of Majorana quasiparticles, these topological material interfaces are commonly studied in static contexts and their response to manipulation remains an open question. We first demonstrate that interface potentials on the topological insulator Bi₂Se₃ can enable the emergence …

Nb3Sn Coating Of Twin Axis Cavity For Srf Applications, J. K. Tiskumara, Jean R. Delayen, G. V. Eremeev, U. Pudasaini, C. E. Reece

Physics Faculty Publications

The twin axis cavity with two identical accelerating beams has been proposed for energy recovery linac (ERL) applications. Nb₃Sn is a superconducting material with a higher critical temperature and a higher critical field as compared to Nb, which promises a lower operating cost due to higher quality factors. Two niobium twin axis cavities were fabricated at JLab and were proposed to be coated with Nb₃Sn. Due to their more complex geometry, the typical coating process used for basic elliptical cavi-ties needs to be improved to coat these cavities. This development advances the current coating system at …

Magnetic Field Sensors For Detection Of Trapped Flux In Superconducting Radio Frequency Cavities, Ishwari Prasad Parajuli, Gianluigi Ciovati, Jean R. Delayen

Physics Faculty Publications

Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. They operate at liquid helium temperatures (2–4 K) to achieve very high quality factors (10¹⁰–10¹¹). Trapping of magnetic flux within the superconductor is a significant contribution to the residual RF losses, which limit the achievable quality factor. Suitable diagnostic tools are in high demand to understand the mechanisms of flux trapping in technical superconductors, and the fundamental components of such diagnostic tools are magnetic field sensors. We have studied the performance of commercially available Hall probes, anisotropic magnetoresistive sensors, and flux-gate magnetometers with …

Experimental Exploration Of Shared Magnetic Phases Between Diverse Systems Of Iron-Pnictide Superconductors, Ryan Scott Stadel

Graduate Research Theses & Dissertations

The exciting field of iron-pnictide superconductors offers unique opportunities for studying the relationship between magnetism and unconventional superconductivity. This is vital to developing an understanding of the microscopic origin of high-temperature superconductivity, which is itself an important step in harnessing such a potentially revolutionary technology.

Polycrystalline and crystalline samples are synthesized over a diverse collection of related iron-pnictide systems including (Ca,Sr,Ba)1-xNaxFe2As2, Ba(Fe1-xCox)2As2 (122s), and LaFeAs1-xPxO, and TbFeAs1-xPxO (1111s). These compounds are characterized through various types of neutron and x-ray diffraction on multiple instruments, as well as muon spin resonance, and magnetic susceptibility measurements.

A thorough investigation into the conditions under …

Superconducting Phase Transition In Inhomogeneous Chains Of Superconducting Islands, Eduard Ilin, Irina Burkova, Xiangyu Song, Michael V. Pak, Dmitri S. Golubev, Alexey Bezryadin

Faculty Publications

We study one-dimensional chains of superconducting islands with a particular emphasis on the regime in which every second island is switched into its normal state, thus forming a superconductor-insulator-normal metal (S-I-N) repetition pattern. As is known since Giaever tunneling experiments, tunneling charge transport between a superconductor and a normal metal becomes exponentially suppressed, and zero-bias resistance diverges, as the temperature is reduced and the energy gap of the superconductor grows larger than the thermal energy. Here we demonstrate that this physical phenomenon strongly impacts transport properties of inhomogeneous superconductors made of weakly coupled islands with fluctuating values of the critical …

Magnesium Diboride Embedded Multi-Walled Carbon Nanotube Yarns, Ujjal Lamichhane

Theses and Dissertations

The discovery of superconductivity in a simple hexagonal binary compound of MgB2 at a relatively high critical temperature ~39 K renewed the interest in the field of superconductivity. Twisted laminar superconducting composite structures based on coiled multi-walled carbon nanotube (MWCNT) yarns were crafted by integrating magnesium and boron homogeneous mixture into the carbon nanotube sheets. After the ignition of the Mg/B/MWCNT system, under the controlled argon environment and uniform heating rate, the high exothermic reaction between magnesium (Mg) and boron (B) with stoichiometric ratio produced the MgB2/MWCNT superconducting composite yarns. The XRD analysis confirmed that the heated sample consists of …