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ABSTRACT:

Understanding chirality, the intrinsic handedness of a system, is important for future technologies using quantum magnetic materials.  Of particular interest are magnetic skyrmions which are chiral and topologically protected, meaning that their spin textures can act as barriers from deformation in crystalline grains.  However, most electron microscopy studies use Lorentz TEM or holography to investigate chirality in skyrmions in nearly perfect single crystals because Fresnel effects may cause signals from grain structures to be mistaken as magnetism when the two are comparable in size.  In this work, we probe nanomagnetism of topological magnetic textures in sputtered thin film of B20 FeGe on Si to study the relationship between magnetic and crystal chirality.  Using 4D-STEM, we find that the vorticity and helicity of these magnetic topological phases are coupled to the crystal chirality.  Furthermore, our work shows that signals from magnetism can be disentangled from crystalline effects for sub-micron grains, enabling a new way to investigate topological magnetism in the presence of small polycrystalline grains. This methodology is important for spintronics and low-power magnetic memory technologies that rely on scalable techniques for large scale manufacturing of real devices. 

Colloquium
Friday, February 10, 2023
3:30 PM
Clark Hall, Room 108
Note special room.

 https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp


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"Next-Generation Black Hole and Neutron Star Collision Simulations"


Zachariah Etienne , University of Idaho
[Host: Alexander Grant]
ABSTRACT:

Perhaps the most significant astronomical discovery of our lifetimes, code-named GW170817, involved the collision of two neutron stars. The collision was detected both by gravitational wave observatories, and traditional electromagnetic telescopes. As neutron stars are made of the densest form of matter in our current Universe, this single "multimessenger" event was a watershed moment in our understanding as to how matter and gravity behave at their most extreme, far beyond what we can study in laboratories on Earth. For the most part, we compare observations against theoretical models to extract science from events like this. Unfortunately, these theoretical models are severely limited both in quality and quantity, leading to a critical need to improve them. Such improvements pose a key challenge to computational astrophysics, as our most detailed models require expensive supercomputer simulations that generate full, non-perturbative solutions of the general relativistic field equations (numerical relativity). After a gentle introduction to multimessenger astrophysics and the challenges associated with multimessenger source modeling, I will outline a new approach aimed at greatly reducing the cost of these simulations. With the reduced cost comes the potential to both perform colliding black hole simulations on the consumer-grade desktop computer, as well as add unprecedented levels of physical realism to colliding neutron star simulations on supercomputers.

Gravity Seminar
Monday, February 13, 2023
1:30 PM
Physics, Room Zoom
Note special room.

Zoom link: https://virginia.zoom.us/j/99508589926?pwd=TUFNMDJZMjZRUTJnaFd3TDgxNi9KZz09

Meeting ID: 995 0858 9926

Password: 441596


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"Stripe discommensuration and spin dynamics in hole-doped 214-nickelates Pr2-xSrxNiO4+δ"


Aveshek Maity , Research Neutron Source Heinz Maier-Leibnitz (FRM II), Technical University of Munich, Garching, Germany
[Host: Despina Louca]
ABSTRACT:

Magnetic excitations in the spin-stripe phases of La-based 214-nickelates have been vigorously explored using inelastic neutron scattering (INS) study for almost last three decades and still have remained an exciting research field, especially to understand their differences yet of their structural similarities with high-Tc 214-cuprates. In view of so far reported two-dimensional antiferromagnetic nature, out-of-plane magnetic excitations are generally not expected in 214-nickelates. In this talk, I will present our recent results from INS measurements on the stripe discommensurated phases of Sr-doped Pr3/2Sr1/2NiO4 samples, showing a compelling evidence for the presence of a sizable out-of-plane interaction suggesting a three-dimensional nature of magnetic excitations near the half-doped region [1,2]. The measured magnetic excitations are in good agreement with our linear spin wave (LSW) theory based calculations in the discommensurated spin stripe models. Additionally, I will discuss the effect of short-range vs. long-range spin stripe correlations on the spin wave dispersion by comparing the results with our INS study on an O-doped sample Pr2NiO4+δ [3].

Condensed Matter Seminar
Thursday, February 23, 2023
4:00 PM
via Zoom, Room TBA
Note special time.
Note special room.

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"TBA"


TBA
[Host: Stefan Baessler]
ABSTRACT:

TBA

Colloquium
Friday, February 24, 2023
3:30 PM
Clark Hall, Room 108
Note special room.

 https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp


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"TBA"


Jan Steinhoff , Max Planck Institute for Gravitational Physics
[Host: David Nichols]
ABSTRACT:

TBA

Gravity Seminar
Monday, February 27, 2023
1:30 PM
Clark Hall - Virtual talk, Room 108
Note special room.

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"TBA"


Jeff Thompson , Princeton University
[Host: Peter Schauss]
ABSTRACT:

TBA

Atomic Physics Seminar
Tuesday, February 28, 2023
3:30 PM
TBA, Room TBA
Note special date.
Note special time.
Note special room.

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"TBA"


Yang Yang , University of Minnesota
[Host: Gia-Wei Chern]
ABSTRACT:

TBA

Condensed Matter Seminar
Thursday, March 2, 2023
4:00 PM
., Room TBA
Note special time.
Note special room.

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"TBA"


Josh Ruderman , NYU
ABSTRACT:

TBA

Colloquium
Friday, March 3, 2023
3:30 PM
Clark Hall, Room 108
Note special room.

https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp


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"TBA"


Cecilia Chirenti , University of Maryland
[Host: Kent Yagi]
ABSTRACT:

TBA

Gravity Seminar
Monday, March 13, 2023
1:30 PM
Physics, Room TBA
Note special room.

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"The Heavy Photon Search at JLAB "


Matt Solt , UVA - Department of Physics
[Host: Prof. Craig Group]
ABSTRACT:

The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for a thermal origin of dark matter sharpen this mass range to within about an MeV to 100 TeV. Most of the stable constituents of known matter have masses in the MeV to GeV range, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well, yet it remains largely unexplored. The Heavy Photon Search (HPS) at Jefferson Lab is a fixed target experiment that uses an electron beam to probe models of thermal dark matter involving sub-GeV dark photons. HPS searches for visibly decaying dark photons through two distinct methods - a resonance search in the e+e- invariant mass distribution and a displaced vertex search for long-lived dark photons. This seminar will give an overview of the theoretical motivations, the main experimental challenges and how they are addressed, the results for the 2016 Engineering Run, and future data and upgrades. In addition, an introduction to the Light Dark Matter eXperiment (LDMX), a planned next generation experiment at SLAC that will search for invisibly decaying dark photons through a missing-momentum experiment, will be presented.

High Energy Physics Seminar
Wednesday, March 15, 2023
4:00 PM
, Room TBA
Note special room.

Join Zoom Meeting: 
https://virginia.zoom.us/j/92287909487
Meeting ID: 922 8790 9487   Passcode: HEPseminar


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" The Heavy Photon Search at JLAB "


Matt Solt , UVA-Physics
[Host: Prof. Craig Group]
ABSTRACT:

The constituents of dark matter are still unknown, and the viable possibilities span a very large mass range. Specific scenarios for a thermal origin of dark matter sharpen this mass range to within about an MeV to 100 TeV. Most of the stable constituents of known matter have masses in the MeV to GeV range, and a thermal origin for dark matter works in a simple and predictive manner in this mass range as well, yet it remains largely unexplored. The Heavy Photon Search (HPS) at Jefferson Lab is a fixed target experiment that uses an electron beam to probe models of thermal dark matter involving sub-GeV dark photons. HPS searches for visibly decaying dark photons through two distinct methods - a resonance search in the e+e- invariant mass distribution and a displaced vertex search for long-lived dark photons. This seminar will give an overview of the theoretical motivations, the main experimental challenges and how they are addressed, the results for the 2016 Engineering Run, and future data and upgrades. In addition, an introduction to the Light Dark Matter eXperiment (LDMX), a planned next generation experiment at SLAC that will search for invisibly decaying dark photons through a missing-momentum experiment, will be presented.

Nuclear Physics Seminar
Wednesday, March 15, 2023
4:00 PM
, Room TBA
Note special date.
Note special time.
Note special room.

Join Zoom Meeting: 
https://virginia.zoom.us/j/92287909487
Meeting ID: 922 8790 9487   Passcode: HEPseminar


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"TBA"


Prof. Yaroslav Tserkovnyak , UCLA
[Host: Prof. Israel Klich]
ABSTRACT:

TBA

Colloquium
Friday, March 24, 2023
3:30 PM
Clark Hall, Room 108
Note special room.

https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp


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"TBA"


Geraint Pratten , University of Birmingham
[Host: David Nichols]
ABSTRACT:

TBA

Gravity Seminar
Monday, March 27, 2023
1:30 PM
Physics, Room Zoom
Note special room.

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"TBA"


Christopher Jarzynski , University of Maryland
[Host: Marija Vucelja]
ABSTRACT:

TBA

Colloquium
Friday, March 31, 2023
3:30 PM
Clark Hall, Room 108
Note special room.

https://web.phys.virginia.edu/Private/Covid-19/colloquium.asp


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"TBA"


Maya Fishbach , Northwestern University
[Host: Kent Yagi]
ABSTRACT:

TBA

Gravity Seminar
Monday, April 10, 2023
1:30 PM
TBA, Room TBA
Note special room.

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To add a speaker, send an email to phys-speakers@Virginia.EDU. Please include the seminar type (e.g. Seminars and Colloquia), date, name of the speaker, title of talk, and an abstract (if available).