Superconducting Proximity Effect in Topological and Spin-orbit Materials

In recent years, there has been a renewed interest in the proximity effect due to its role in the realization of topological superconductivity. During this talk, we discuss several results that have been obtained in the field of proximity-induced superconductivity and relate the results to the search for Majorana fermions. First, we show that repulsive electron-electron interactions can induce a non-Majorana zero-energy bound state at the interface between a conventional superconductor and a normal metal and propose an experimental setup to observe such a state.

SU(4) Symmetry in Graphene Landau Levels: Break it or Not?

Landau levels in graphene have an approximate SU(4) symmetry in the spin and valley space. In this talk, I will present two contrasting symmetry patterns of quantum Hall states in graphene. At the charge neutrality point, the quantum Hall states spontaneously break the SU(4) symmetry, and the ground state is pinned down by the lattice-scale interactions and the Zeeman energy. I will describe an enlarged SO(5) symmetry identified in the valley-symmetry breaking interaction.

Coherent Charged Pion Production at MINERvA

This seminar has been rescheduled for Monday, Nov. 23, 11 a.m., Bldg. 362, Rm. F108.

Neutrino-induced coherent charged pion production on nuclei is a rare, inelastic interaction that produces a charged lepton and pion in the forward direction while leaving the nucleus intact. Understanding this process at few GeV neutrino energy is important for precision measurements of neutrino oscillation parameters.

Advances in Coupled‐cluster Computations of Nuclei

In this talk I will present recent highlights in ab initio computations of nuclei using coupled‐cluster theory with interactions and currents from chiral effective field theory. The topics I will discuss include: (i) accurate nuclear binding energies and radii of light and medium mass nuclei from a chiral interaction, (ii) the neutral- and weak-charge distributions and electric dipole polarizability of 48Ca, quantities that are currently targeted by precision measurements worldwide, and (iii) the microscopic origins of the quenching of the axial vector coupling GA.

Covariant Derivative Expansion: Generic Calculation of SM EFT Wilson Coefficient at One Loop Level

In this talk I will show a novel calculation tool based on the covariant derivative expansions of the Coleman-Weinberg potential, which can match an arbitrary UV theory to the pure bosonic SM operator set. This method has advantage of getting all the operators simultaneously, being universal for specific models, and always giving analytical results. The matching has been generalized to fermionic models, and nondegenerated large scales.

Employee Spotlight: Muge AcikNovember 17, 2015

Joseph Katz Fellow in Chemistry

Argonne Researchers Receive Accolades for ACCOLADESNovember 17, 2015

Two researchers from Argonne National Laboratory – Shashi Aithal, a computational scientist in the Computing, Environment and Life Sciences directorate, and Stefan Wild, a computational mathematician in the Mathematics and Computer Science Division – received the HPC Innovation Excellence Award at SC15.

Phase Diagram and Vortex Pinning of Iron-based Superconductors Tuned by Irradiation Induced Disorder

In my presentation I will discuss two applications of disorder controlled by energetic particle irradiation. First in the exploration of composition – temperature (x-T) phase diagram of canonical iron-based superconductor Ba(FeAs1-xPx)2. Upon isovalent substitution of As by P, temperature of spin density wave (SDW) transition decreases and dome of superconducting phase appears.

In the region of intersection of SDW transition line with superconducting dome several phenomena attract attention: