UConn Researcher an Architect for Astronomical Survey Making Observations Toward a New Understanding of the Cosmos
November 2, 2020 – Elaina Hancock – UConn Communications The Sloan Digital Sky Survey’s fifth generation – a groundbreaking project to bolster our understanding of the formation and evolution of galaxies, including the Milky Way – collected its very first observations on the evening of October 23. Image: The Sloan Digital Sky Survey’s fifth generation […]
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The passing of UConn Physics Professor Emeritus, Arnold Russek
Arnold Russek, a theoretical atomic physicist, born July 13, 1926, in New York, passed away on October 13th, 2020, in Colorado. As a young man of 18, he served honorably as a radio engineer in the Pacific during WWII. He earned his Ph.D. at the Courant Institute at New York University in 1953, and taught […]
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AAS Author Interview with Gloria Fonseca Alvarez
UConn graduate student Gloria Fonseca Alvarez was featured with a video in the Author Interview series produced by the American Astronomical Society (AAS). In this video, Gloria talks about her work to understand the inner environments of black holes. The paper highlighted in the video shows that the orbits of emission-line gas around supermassive black holes are often smaller than expected from previous observations.
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Stretching Makes Superconductor
Most superconductors only work when they’re super cold. Chemists and metallurgists have experimented with different combinations of elements for years, trying to get superconductors that work at temperatures close to room temperature. Sochnikov and his students are thinking about it differently. What if mechanical changes such as squeezing or stretching could make a material a superconductor?
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Longtime Science Pioneer Passes Away
Throughout her long life, Cynthia Peterson educated and enriched her family, her students, and her community through science, discovery, and a lifelong enthusiasm for teaching prospective scientists. Through community outreach and during her many years as a professor, Cynthia taught many that wonderment can be found simply by looking up at the night sky.
[Read More]Recent Events
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We will have two presentations and by Los Alamos theorists:, Condensed Matter Physics Seminar9:30am
11/24
We will have two presentations and by Los Alamos theorists:, Condensed Matter Physics Seminar
Tuesday, November 24th, 2020
09:30 AM - 11:00 AM
Storrs Campus online
We will have two presentations and by Los Alamos theorists:
9:30-10:00 Shizeng Lin (Los Alamos)
Switching of valley polarization and topology in twisted bilayer graphene by electric currents
The associated manuscript is available at https://arxiv.org/abs/2002.02611.
10:00-10:30 Jian Xin Zhu (Los Alamos)
Signatures of Spin Polarized Fermi Arcs in the Quasiparticle Interferences of CeBi
Ref.: arXiv:2008.10628
10:30-11:00 Discussion
Zoom Meeting:
https://kth-se.zoom.us/j/62068067873 -
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Quantum Matter and Dark Matter Detection ", Graduate Student Seminar12:15pm
11/20
Prof A. Balatsky, Department of Physics, University of Connecticut, "Dynamic Quantum Matter and Dark Matter Detection ", Graduate Student Seminar
Friday, November 20th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof A. Balatsky,
Department of Physics,
University of Connecticut
Dynamic Quantum Matter and Dark Matter Detection
I will give an overview of activities in the group: starting with the challenge and recent theoretical and experimental progress in identifying the dynamic and entangled orders in quantum materials. As a simple, yet new case I will describe the phenomenon of dynamic multiferroicity in STO and comment on the challenge of detection of quantum hidden orders that require multimode quantum probes. Further, I will discuss proposed applications of quantum materials outside of "usual suspect list", like the use of quantum materials as detectors for Dark Matter. -
Graduate Student Kemal Tezgin, Department of Physics, University of Connecticut, "Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions ", PhD Dissertation Defense1:00pm
11/18
Graduate Student Kemal Tezgin, Department of Physics, University of Connecticut, "Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions ", PhD Dissertation Defense
Wednesday, November 18th, 2020
01:00 PM - 03:00 PM
Storrs Campus Video meeting
Graduate Student Kemal Tezgin, Department of Physics,
University of Connecticut
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions
The understanding of the internal structure of the proton and other strongly interacting particles is at the forefront of modern nuclear physics research. Generalized Parton Distribution Functions (GPDs) are a powerful tool to advance the understanding of the hadron structure. In addition to the information about the one- dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) known from studies of high energy deep-inelastic reactions, GPDs also carry information on the distribution of partons in the transverse plane, and allow us in this way to access the three-dimensional structure of the nucleon. GPDs can be studied in hard-exclusive reactions and contain also information on the energy-momentum tensor form factors which will allow us to gain insights on quantities like pressure or angular momentum distribution inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor form factors and densities, and all leading-twist GPDs in the bag model. This quark model provides a consistent theoretical framework to investigate many general concepts that have recently attracted interest, and allows one to study insightful limits like the large-Nc limit, heavy-quark limit, or the non-relativistic limit. Another important aspect of this thesis is the discussion of the monopole and quadrupole contributions to the angular momentum density. Finally, the description of pseudoscalar meson production in exclusive processes in terms of GPDs is discussed in the Goloskokov-Kroll model and implemented in the PARTONS framework, a software development project which will provide direct support for experiments at the Jefferson National Lab and the future Electron-Ion Collider. -
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions , Doctoral Dissertation Oral Defense Of Kemal Tezgin1:00pm
11/18
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions , Doctoral Dissertation Oral Defense Of Kemal Tezgin
Wednesday, November 18th, 2020
01:00 PM - 02:30 PM
Storrs Campus Zoom
Theoretical and Phenomenological Studies of the Nucleon Structure in High Energy Reactions
In high energy collisions, Parton Distribution Functions (PDFs) are fundamental objects to describe one-dimensional collinear momentum distributions of partons (quarks, anti-quarks, and gluons) inside the nucleon. In addition to PDFs, Generalized Parton Distribution Functions (GPDs) also carry information on the distribution of partons in the transverse plane to its motion and allow us to access the three-dimensional structure of the nucleon. On the other hand, energy-momentum tensor (EMT) densities allow us to access the pressure, shear forces, and angular momentum density inside the nucleon. The goal of this thesis is to deepen our understanding of the three-dimensional structure of the nucleon. We investigate energy-momentum tensor (EMT) form factors and densities, and all leading-twist GPDs in the bag model, formulated in the large-N_c limit. We also evaluate all leading-twist chiral-odd GPDs of the relativistic nucleon in the bag model. The consistency of this quark model allows us to investigate many general concepts that have recently attracted interest, including pressure, shear forces, and angular momentum density. Another important aspect of this thesis is to discuss that the monopole and quadrupole contributions to the angular momentum density can be generated from each other uniquely in a model-independent way. The last chapter is dedicated to the phenomenology of GPDs and the Goloskokov-Kroll model's implementation in the PARTONS framework for pseudoscalar meson production in exclusive processes. -
Dr. Vivienne Baldassare, Washington State Univeristy , "Searching for active galactic nuclei in low-mass galaxies via optical variability", Astronomy Seminar11:00am
11/18
Dr. Vivienne Baldassare, Washington State Univeristy , "Searching for active galactic nuclei in low-mass galaxies via optical variability", Astronomy Seminar
Wednesday, November 18th, 2020
11:00 AM - 12:00 PM
Storrs Campus online
Dr. Vivienne Baldassare, Washington State Univeristy
Searching for active galactic nuclei in low-mass galaxies via optical variability
The present-day population of supermassive black holes in low-mass galaxies offers a window into massive black hole formation in the early universe. While we cannot yet observe the formation of "black hole seeds" at high redshift, the fraction of small galaxies that host a supermassive black hole -- and the properties of those black holes -- are thought to depend on the mechanism by which they form. However, black holes in the smallest galaxies can be difficult to find, requiring creative new approaches. I will discuss recent work showing that long-term optical photometric variability in low-mass galaxies can identify active galactic nuclei that are missed by other selection techniques. I will present an analysis of the nuclear variability of more than 70,000 nearby galaxies and discuss our sample of low-mass, variability-selected supermassive black holes. Using this sample, we also begin to place meaningful constraints on the present-day black hole occupation fraction at low galaxy stellar masses.
Webex link: https://uconn-cmr.webex.com/meet/yah14006 -
Prof A. Puckett, Department of Physics, University of Connecticut, Graduate Student Seminar12:15pm
11/13
Prof A. Puckett, Department of Physics, University of Connecticut, Graduate Student Seminar
Friday, November 13th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Prof A. Puckett,
Department of Physics,
University of Connecticut
Sub-femtoscale structure of strongly interacting matter from "hard" electron-nucleus collisions
The emergence of nucleon structure and dynamics from strong interactions among its elementary quark and gluon constituents is one of the most difficult and interesting problems in all of physics. The strong interaction, NOT the electroweak Higgs mechanism, is responsible for the dynamical generation of the mass of approximately 98% of all ordinary matter in the universe. Scattering of ultrarelativistic electron beams from nucleon and nuclear targets is the tool of choice for the precision study of nucleon structure. The Super BigBite Spectrometer (SBS) at Jefferson Lab, a novel device currently being installed in JLab's experimental Hall A, with the first beam tentatively expected in 2021, will facilitate a focused program of high-impact nucleon structure measurements in electron-nucleon scattering at large momentum transfer. In this talk I will give an overview of the upcoming SBS program and opportunities for graduate student involvement. -
Professor Saroj Prasad Dash, Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Sweden, "Spin Current in Topological Quantum Materials", Condensed Matter Physics Seminar10:00am
11/10
Professor Saroj Prasad Dash, Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience, Chalmers University of Technology, Sweden, "Spin Current in Topological Quantum Materials", Condensed Matter Physics Seminar
Tuesday, November 10th, 2020
10:00 AM - 11:00 AM
Storrs Campus online
Professor Saroj Prasad Dash,
Quantum Device Physics Laboratory, Dept. Microtechnology and Nanoscience,
Chalmers University of Technology, Sweden
Spin Current in Topological Quantum Materials
An outstanding feature of topological quantum materials is their unique spin topology in the electronic band structures with an expected novel charge‐to‐spin conversion effects. In the Weyl semimetal candidate WTe2 we observed both conventional1 and unconventional2 charge‐to‐spin conversion effects at room temperature. In addition to the conventional spin Hall and Rashba--Edelstein effects, we also measured an unconventional charge‐to‐spin conversion component in WTe2. Such a large spin polarization can be possible in WTe2 due to a reduced crystal symmetry combined with its large spin Berry curvature, spin--orbit interaction with a novel spin‐texture of the Fermi states. We also investigated giant Rashba spin-orbit materials BiTeBr to detect the current induced spin polarization at room temperature.3 Furthermore, we integrated graphene with a topological insulator4,5 in van der Waals heterostructures6 to engineer proximity-induced spin-charge conversion phenomena. In these heterostructures, we experimentally demonstrate a gate-tunable spin-galvanic effect at room temperature, allowing for efficient conversion of a non-equilibrium spin polarization into a transverse charge current.7 These findings provide an efficient route for realizing all-electrical and gate-tunable spin phenomenon in topological materials and their heterostructures.
References:
1. Observation of charge to spin conversion in Weyl semimetal at room temperature.
B Zhao, D Khokhriakov, Y Zhang, H Fu, B Karpiak, AM Hoque, X Xu, Y Jiang, B Yan, SP Dash.
Physical Review Research 2 (1), 013286 (2020).
2. Unconventional charge-to-spin conversion Weyl Semimetal WTe2. B Zhao, B Karpiak, D Khokhriakov, A Johansson, AM Hoque, X Xu, Y Jiang, I Mertig, SP Dash. Advanced Materials, 2000818 (2020).
3. Electrically controlled spin injection from giant Rashba spin-orbit conductor BiTeBr"
Z Kovács-Krausz et al., Nano Letters 20, 7, 4782--4791 (2020).
4. Origin and evolution of surface spin current in topological insulators
A Dankert, P Bhaskar, D Khokhriakov, IH Rodrigues, B Karpiak, MV Kamalakar, S Charpentier, I Garate, SP Dash.
Phys. Rev. B 97, 125414 (2018).
5. Room Temperature Electrical Detection of Spin Polarization in Topological Insulators
A Dankert, J. Geur, M.V. Kamalakar, SP Dash;
Nano Letters 15 (12) 7976 (2015).
6. Tailoring emergent spin phenomena in Dirac material heterostructures.
D Khokhriakov, A. W. Cummings, K Song, M Vila, B Karpiak, A Dankert, S Roche and SP. Dash.
Science Advances, 4, 9, eaat9349 (2018)
7. Gate-tunable Spin-Galvanic Effect in Graphene - Topological insulator van der Waals Heterostructures at Room Temperature. D Khokhriakov, AM Hoque, B Ka -
Jacob Franklin, Department of Physics, University of Connecticut, "Quantum sensing for nanoscale magnetic imaging", Graduate Student Seminar12:15pm
11/6
Jacob Franklin, Department of Physics, University of Connecticut, "Quantum sensing for nanoscale magnetic imaging", Graduate Student Seminar
Friday, November 6th, 2020
12:15 PM - 01:15 PM
Storrs Campus online
Jacob Franklin,
Department of Physics,
University of Connecticut
Quantum sensing for nanoscale magnetic imaging
Nanoscale resolution of the properties of materials often plays a crucial role in the pursuit of explanations for exotic phenomena in such materials. These phenomena, such as high temperature superconductivity and frustrated magnetic states, have very exciting potential for practical applications, such as quantum computing. In the Sochnikov Lab, we use state-of-the-art sensors called SQUIDs to probe the magnetic properties of materials and generate magnetic maps at their surfaces. These images are on the order of micrometers in spatial resolution and play an important role in the study of the aforementioned phenomena, for example, because they can be used to analyze the formation and interaction of domains in response to parameters like temperature, auxiliary magnetic field, or strain. I will present some of the fundamental materials research work I have done in the Sochnikov Lab, in which I and my lab mates have taken a direct role in both measurement and analysis. In addition, I will share my experience with instrumentation development projects like the construction of custom-built piezoelectric scanners, the improvement of wiring in our cryostats, the coding of a GUI system for the plotting of data, and the improvement of our data interpolation functions.