Studies of inhomogeneous superconducting states in novel materials

I provide detailed studies of two types of novel superconducting systems. In the first, I examine the effect of thermal (Gaussian) magnetic fluctuations on the superconducting transition of paramagnetically-limited superconductors under a Zeeman magnetic field. I consider transitions into both the uniform and the modulated (Fulde-Ferrell-Larkin-Ovchinnikov) superconducting states. I derive the Landau free energy expansion in powers of the superconducting order parameter, allowing for competition between the magnetic fluctuations and the superconducting order. I determine the order of the transition at the upper critical field and find that the fluctuations drive the transition, usually second-order, to first order at intermediate temperatures for both the uniform and modulated states. I also compute the thermodynamic signatures of the transition along the upper critical field. I use these results to help explain experiments on the heavy-fermion superconductor CeCoIn5, for which the superconducting transition is first-order at low temperatures and large magnetic fields. In the second study, I use a T-matrix approach to examine the resonant state generated by a single, non-magnetic impurity in multi-band superconducting systems. I consider extended s-wave symmetry of the superconducting gap and allow for anisotropy of the gap along the Fermi surface. I derive analytic expressions for the Green\u27s functions in the continuum and identify the criteria for the formation of the impurity states, emphasizing the role the band structure plays for existence of the resonant state. I then use these results to guide and explain the results of numerical studies of the impurity states on a lattice. For my numerical approach, I use dispersion relations appropriate for the description of the ferropnictides, a recently-discovered family of iron-based superconductors. I map the impurity state in real-space and emphasize how the features of these states can help identify the nodal structure of the gap on each of the Fermi surface sheets

Pauli-Limited Superconductivity with Classical Magnetic Fluctuations

We examine the effect of classical magnetic fluctuations on the phase diagram of paramagneticallylimited two-dimensional superconductors under a Zeeman magnetic field. We derive the free energy expansion in powers of the superconducting order parameter and analyze the character of the normalsuperconducting transition. While the transition is of the second order for all temperatures in the absence of magnetic fluctuations, we find that proximity to magnetism drives both the transition into the uniform state and that into the modulated (Fulde-Ferrell-Larkin-Ovchinnikov, FFLO) state to first order at intermediate temperatures. We compute the thermodynamic signatures of the normal-superconducting transition along the upper critical field.Comment: 16 pages, 9 figure

Reflections on the Origin and Nature of Greek Tragedy

(Statement of Responsibility) by III, Robert D. Beaird(Thesis) Thesis (B.A.) -- New College of Florida, 1972RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.Faculty Sponsor: Hoppin, Mario

COVID‐19 in hospitalized lung and non‐lung solid organ transplant recipients: A comparative analysis from a multicenter study

Lung transplant recipients (LTR) with coronavirus disease 2019 (COVID-19) may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with COVID-19 to compare mortality by 28 days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with COVID-19, 1,081 (66%) were hospitalized including 120/159 (75%) LTR and 961/1457 (66%) non-lung SOTR (p = .02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p = .032), and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p = .04). Among LTR, chronic lung allograft dysfunction (aOR 3.3, 95% CI 1.0-11.3, p = .05) was the only independent risk factor for mortality and age >65 years, heart failure and obesity were not independently associated with death. Among SOTR hospitalized for COVID-19, LTR had higher mortality than non-lung SOTR. In LTR, chronic allograft dysfunction was independently associated with mortality

Covid-19 in hospitalized lung and non-lung solid organ transplant recipients: a comparative analysis from a multicenter study.

Lung transplant recipients (LTR) with Covid-19 may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with Covid-19 to compare mortality by 28-days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with Covid-19, 1,051 (65%) were hospitalized including 117/159 (74%) LTR and 934/1457 (64%) non-lung SOTR (p=0.02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p=0.035) and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p=0.05). Among LTR, independent risk factors for mortality included single lung transplant (aOR 2.8, 95% CI 1.0-7.7, p=0.04) and chronic lung allograft dysfunction (aOR 3.6, 95% CI 1.0-12.4, p=0.05), but not age \u3e65 years, heart failure, or obesity. Among SOTR hospitalized for Covid-19, LTR had higher mortality than non-lung SOTR. In LTR, single lung transplant and chronic allograft dysfunction were independently associated with mortality