Academic Calendar

semester, 2017


Monday, January 2nd 2017

Monday, January 16th 2017

Monday, February 20th 2017
10:00 am:
Thesis Defense in Keller Hall 4-178A
Speaker: Tao Qu, University of Minnesota
Subject: Ferromagnetic Material Properties and Performance in Spintronic Devices
This is the public portion of Ms. Qu's thesis defense. Her advisor is Randall H. Victora.

Thursday, March 9th 2017
11:00 am:
Thesis Defense in PAN 110
Speaker: Yangmu Li
Subject: New insights into phase diagram and the emergence of superconductivity for the electron-doped cuprate superconductors
This is the public portion of Mr. Li's thesis defense. His advisor is Professor Martin Greven.

After three decades of enormous scientific inquiry, the emergence of superconductivity in the cuprates remains an unsolved puzzle. One major challenge has been to arrive at a satisfactory understanding of phase transitions in the multi-parameter phase space. A related challenge has been to achieve a unified understanding of the hole- and the electron-doped compounds. Here, I report detailed neutron scattering, muon spin rotation/relaxation and magnetoresistivity measurements for the archetypal electron-doped cuprate Nd2-xCexCuO4+d that, in combination with prior data, provide crucial links between the normal and superconducting states and between the electron- and the hole-doped parts of the phase diagram. The revised electron-doped side of the phase diagram features a disorder-smeared first-order phase transition between the antiferromagnetic and bulk superconducting ground states. The characteristics of the normal state and those of the superconducting state consistently indicate two-band (electron and hole) features and clearly point to hole-driven superconductivity in these nominally electron-doped materials. These insights allow us to extend the Uemura-scaling between the superconducting transition temperature and the hole superfluid density to the electron-doped cuprates.


Friday, March 17th 2017

Thursday, April 20th 2017
7:00 pm:
Van Vleck Public Lecture in Ted Mann Concert Hall
Speaker: Arthur B. McDonald, Queen's University and Sudbury Neutrino Observatory
Subject: A Deeper Understanding of the Universe from 1.2 miles Underground

By going 1.2 miles underground and creating an ultra-clean laboratory it is possible to address some very fundamental questions about our Universe: How does the Sun burn?; What are the dark matter particles making up 27% of our Universe?; What are the properties of neutrinos, elusive particles that are one of the fundamental building blocks of nature?. With the Sudbury Neutrino Observatory (SNO) we were able to observe new properties of neutrinos that go beyond the Standard Model of Elementary Particles and also confirm that the models of how the Sun burns are very accurate. With the expanded laboratory SNOLAB we are welcoming the world in collaborative experiments that are looking for the properties of Dark Matter particles, seeking further properties of neutrinos and looking for neutrino signals from supernovae in our galaxy, from the Earth and from the Sun. The advantages created by the development of one of the lowest radioactivity laboratories in the world and the resulting fundamental science will be described.


Thursday, May 11th 2017
12:15 pm:
Thesis Defense in PAN 110
Speaker: Andy Julin, University of Minnesota
Subject: Measurement of DD Decays from the psi(3770) Resonance
This is the public portion of Mr. Julin's thesis defense. His advisor is Ron Poling.

We measure the production cross section of e^+ e^− → ψ(3770) → DD near the peak of the ψ(3770) resonance. The (69.80 ± 0.03) pb^−1 of e^+ e^− annihilation data used were collected in 2010 over a center-of-mass energy range of 3.735 GeV to 3.870 GeV. From previously observed e^+ e^− → DD cross section measurements, this shape cannot be explained by a single Breit-Wigner. Instead, in this analysis we fitted the cross section by including interference effects from non-resonant DD production, and measured the mass and width of the ψ(3770) more precisely than previous results.


Friday, May 12th 2017
11:00 am:
Thesis Defense in PAN 110
Speaker: Xiaoyu Wang, University of Minnesota
Subject: Interplay between charge, spin and superconducting properties in copper-based and iron-based superconductors.
This is the public portion of Mr. Wang's thesis defense. His advisor is Rafael Fernandes.

Saturday, May 13th 2017
3:35 pm:

Monday, May 22nd 2017

Monday, May 29th 2017

Tuesday, June 6th 2017
09:00 am:
Please contact Bill Voje at to sign up for class.

Friday, June 9th 2017

Monday, June 12th 2017

Wednesday, June 14th 2017
2:00 pm:
Thesis Defense in PAN 110
Speaker: Mehdi Lamee, University of Minnesota
Subject: The Ionized Intergalactic Medium and its Influence on Galaxies and Galaxy Clusters
This is the public portion of Mr. Lamee's PhD examination, advisor L. Rudnick

Friday, June 16th 2017
10:30 am:
Thesis Defense in PAN 210
Speaker: Jiaming Zheng, University of Minnesota
Subject: Dark Matter Models in Non-Supersymmetric SO(10) Unification Theories
This is the public portion of Mr. Zheng's thesis defense. His advisor is Keith Olive.

We studied systematically non-supersymmetric SO(10) models that contain dark matter candidates. The stability of the dark matter particle is guaranteed by a remnant Z_2 subgroup of SO(10). We build models base on various dark matter production mechanisms and check them against several phenomenological constraints, such as the light neutrino masses, direct detection bounds on dark matter candidates and the proton decay lifetime. The requirement of gauge coupling unification offers a severe constraint on the model building. We also demonstrate that the vacuum stability problem of the Standard Model can be evaded by one of our scalar dark matter models.


Saturday, June 24th 2017
8:30 pm:
Universe in the Park in Nerstrand Big Woods State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Saturday, July 1st 2017
8:30 pm:
Universe in the Park in William O'Brien State park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Tuesday, July 4th 2017

Friday, July 7th 2017
11:00 am:
Thesis Defense in PAN 110
Speaker: Yuriy Sizyuk, University of Minnesota
Subject:  4d and 5d compounds as the new frontier of the anisotropic spin physics
This is the public portion of Mr. Sizyuk's thesis defense. His advisor is Natalia Perkins.

My talk will be on the strong spin-orbit coupling as a source of heavily anisotropic magnetic Hamiltonians in 4d and 5d compounds, most notably iridates and RuCl3. I will discuss the derivation of the anisotropic Hamiltonians from microscopic parameters, and the competition and cooperation of different interactions that lead to the complex magnetic states in iridates and RuCl3.


Saturday, July 8th 2017
8:30 pm:
Universe in the Park in Afton State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Monday, July 10th 2017

Thursday, July 13th 2017
09:30 am:
Thesis Defense in PAN 110
Speaker: Samuel Ducatman, University of Minnesota
Subject: Magnetic Excitations of Hyperhoneycomb beta-Lithium Iridate.
This is the public portion of Mr. Ducatman's thesis defense. His advisor is Natalia Perkins.

Friday, July 14th 2017
2:30 pm:
Thesis Defense in 110 PAN
Speaker: Han Fu, University of Minnesota
Subject: Electron transport in SrTiO3 accumulation layers and semiconductor nanocrystal films
This is the public portion of Ms. Fu's Thesis Defense. Her advisor is Boris Shklovskii

We start from the low temperature conductivity of electron accumulation layers induced by the very strong electric fi eld at the surface of STO sample. Due to the strongly nonlinear lattice dielectric response, the three-dimensional density of electrons n(z) in such a layer decays with the distance from the surface z very slowly as n(z) ~1/z^{12/7}. We show that when the mobility is limited by the surface scattering, the contribution of such a tail to the conductivity diverges at large z because of growing time electrons need to reach the surface. We explore truncation of this divergence by the fi nite sample width, by the bulk scattering rate, by the back gate voltage, or by the crossover to the bulk linear dielectric response with the dielectric constant \kappa. As a result we arrive at the anomalously large mobility, which depends not only on the rate of the surface scattering, but also on the physics of truncation. Similar anomalous behavior is found for the Hall factor, the magnetoresistance, and the thermopower.

Finally, we switch to the study of NC films. We focus on the variable-range hopping of electrons in semiconductor NC fi lms below the critical doping concentration nc at which fi lms become metallic. The hopping conductivity is then described by the Efros-Shklovskii law which depends on the localization length of electrons. We study how the localization length grows with the doping concentration n in the film of touching NCs. For that we calculate the electron transfer matrix element t(n) between neighboring NCs when NCs touch by small facets. We use the ratio of t(n) to the disorder-induced NC level dispersion to fi nd the localization length of electrons due to the multi-step elastic co-tunneling process.

8:00 pm:
Universe in the Park in Dodge Nature Center
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Friday, July 21st 2017
2:00 pm:
Thesis Defense in PAN 110
Speaker: Chun Chen, University of Minnesota
Subject: A New Type of Many-Body Majorana Zero Modes in Fermionic Flux Ladder Model
This is the public portion of Mr. Chen's thesis defense. His advisor is Fiona Burnell.

One-dimensional topological superconductors and superfluids are typically classified and understood through Bogoliubov–de Gennes mean-field Hamiltonians. This raises the question of whether they can exist in truly one-dimensional systems where particle number is conserved. We discuss a new mechanism by which Majorana zero modes can arise in a number-conserving Fermi ladder. This interaction-enabled topological phase is protected by a unitary symmetry that is not related to any microscopic fermion-parity symmetry.

8:30 pm:
Universe in the Park in Cedar Creek Ecosystem Science Reserve
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Saturday, July 29th 2017
8:30 pm:
Universe in the Park in Afton State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Friday, August 4th 2017
8:30 pm:
Universe in the Park in Mille Lacs kathio State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Saturday, August 5th 2017
8:30 pm:
Universe in the Park in Father Hennepin State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Friday, August 11th 2017
8:30 pm:
Universe in the Park in William O'Brien State park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Saturday, August 12th 2017
8:30 pm:
Universe in the Park in Lake Maria State Park
Presentations typically run from 8:30 to 10:00 or 11:00pm, including telescope observing. This event is free and open to the public, though a vehicle permit is usually required to enter state parks.

Sunday, August 13th 2017
12:00 pm:
Pre-eclipse Block Party in Outdoor space between Physics and Nanotechnology Building and Akerman Hall
Speaker: James Flaten, Aerospace Engineering and Mechanics; Lindsay Glesener, School of Physics and Astronomy
Subject: "Live-streaming the Solar Eclipse from the Stratosphere," and "A Rare Look at the Sun's Corona."

1) (Flaten) NASA’s Space Grant Consortia from 30 states are fielding teams of college students to develop light-weight video-telemetry systems to live stream the view of the shadow of the Moon from the stratosphere. Over 50 ballooning teams are preparing to fly into the path of totality from Oregon all the way to South Carolina. The U of M team will show off their flight units and ground station hardware and talk about their preparations to participate in this nationwide project.

2) (Glesener) Solar eclipses are beautiful and fascinating events, and they also offer rare opportunities to study the elusive corona -- the outermost layer of the Sun's atmosphere. With a temperature hundreds of times greater than that of the Sun's surface, the mysterious corona is governed by strong magnetic fields that control all structure and motion. Explore the fascinating nature of the outer layers of the Sun and learn how you can contribute to solar science while you view the eclipse!


Friday, August 18th 2017

Monday, August 28th 2017
2:00 pm:
Thesis Defense in Akerman 225
Speaker: Quentin Ebner, University of Minnesota
Subject: The Effects of Alloy Disorder and Density on Non-Equilibrium Transport in Two-Dimensional Electron Gases

Tuesday, August 29th 2017
12:15 pm:
Thesis Defense in Tate 301-20
Speaker: Melanie Galloway, University of Minnesota
Subject: Morphology is a Link to the Past: examining formative and secular galactic evolution through morphology
This is the public portion of Ms. Galloway's thesis defense. Her advisor is Lucy Fortson

Monday, September 4th 2017

Thursday, September 7th 2017
09:00 am:
Thesis Defense in Tate 301-20
Speaker: Cheng-Hsien Li, University of Minnesota
Subject: Astrophysics and Physics of Neutrino Detection
This is the public portion of Mr. Li's thesis defense. His Advisor is Yongzhong Qian.

A galactic core-collapse supernova is a powerful neutrino source of which the signals can be picked up by a water Cherenkov detector on the Earth. From an astrophysical point of view, the signals reveal the dynamics of core-collapse supernova explosion and the subsequent cooling of a proto-neutron star (PNS). In this regard, we compare the neutrino emission profiles from the recent 1D hydrodynamics simulation by Mirizzi et al. (2016) with the historical SN1987A data through a statistical goodness-of-fit test. Such test reveals the tension between the data and rapid PNS cooling prescribed by the convection treatment employed in the simulation. The implications will be discussed. From a quantum-mechanical point of view, on the other hand, the supernova neutrino flux is so intensive such that a huge degree of wave-packet overlap is estimated. Such overlap may give rise to an interference effect known as the Hanbury Brown and Twiss (HBT) effect. We derive the solution for a 3D Gaussian wave packet and, with such solution, the joint-detection probability. We demonstrate that an observable interference occurs if the joint-detection were to render the two detected neutrinos in the same phase space cell. Upon further examination, however, we conclude that such effect is difficult to observe from neutrinos in practical experimental settings.


Thursday, September 14th 2017
All School undergraduate majors and graduate students are welcome to attend.

Monday, September 18th 2017
12:30 pm:
National Postdoc Association Townhall in Mayo Memorial Auditorium, Room 3-100

We will be reviewing what we have done over the past year, including: explaining changes to the FLSA and its status under the new administration, advocating for postdoctoral rights with the White House, travelling to DC, changing our position in the University Senate, changing mentoring at the U, trying to create a career office, advocating with the National Postdoc Association, and more.

Food to be provided

More information about this event can be found on the PDA Website.


Tuesday, September 19th 2017
2:00 pm:
National Postdoc Association Seminar in Weaver-Densford Hall W2-110
Speaker: Noro Andriamanalina
Subject: My IDP

A seminar reviewing an efficient process at creating the professional agreement that guarantees a successful postdoctoral appointment and improving the relationship between you and your mentor.

More information about this event can be found on the PDA Website.


Wednesday, September 20th 2017
3:00 pm:

An ice cream social for postdocs on campus! Show up, have some free ice cream, play games, talk to your fellow coworkers, and have a chance to relax on campus!

More information about this event can be found on the PDA Website.


Friday, September 22nd 2017

The postdoc research symposium is a poster session where postdocs will have the chance to interact with judges and representatives from local industry. There will be awards both from the PDA and local companies and the awards ceremony will feature various speakers

You can register posters for the poster session here, there is no fee, there is a limit to the number of poster spots available.

If you have questions, please direct them to pda@umn.edu. We hope you'll take advantage of this opportunity to build a stronger postdoc community at the U.

Limited poster printing is available. Contact pda@umn.edu with questions.

More information about this event can be found on the PDA Website.


Saturday, September 23rd 2017
08:30 am:
An International Conference Honoring Mitchell Luskin on the Occasion of his 65th Birthday

Summary: Multiscale modeling, theory, and computation have made fundamental contributions to many areas of physical, chemical, and biological sciences. Recent theoretical and experimental advances present new challenges for multiscale theory and computation. This conference will seek to stimulate new approaches and collaborations by bringing together both senior and junior researchers with expertise spanning molecular to continuum scales and stochastic to deterministic methods.

Some examples of talks of possible interest to Physics on the schedule:
Epitaxially Strained Elastic Films: Quantum Dots and Dislocations
The Problem of Small Temperatures in a Quantum Gas
Multiscale Dynamical Systems
Wandering in Flatland: the Wonders of 2D Materials
"Metastability: a Journey from Stochastic Processes to Semiclassical Analysis
Spin-Diffusions and Diffusive Molecular Dynamics

Register here


Sunday, September 24th 2017
An International Conference Honoring Mitchell Luskin on the Occasion of his 65th Birthday

Summary: Multiscale modeling, theory, and computation have made fundamental contributions to many areas of physical, chemical, and biological sciences. Recent theoretical and experimental advances present new challenges for multiscale theory and computation. This conference will seek to stimulate new approaches and collaborations by bringing together both senior and junior researchers with expertise spanning molecular to continuum scales and stochastic to deterministic methods.

Some examples of talks of possible interest to Physics on the schedule:
Epitaxially Strained Elastic Films: Quantum Dots and Dislocations
The Problem of Small Temperatures in a Quantum Gas
Multiscale Dynamical Systems
Wandering in Flatland: the Wonders of 2D Materials
"Metastability: a Journey from Stochastic Processes to Semiclassical Analysis
Spin-Diffusions and Diffusive Molecular Dynamics

Register here


Monday, September 25th 2017
08:30 am:
An International Conference Honoring Mitchell Luskin on the Occasion of his 65th Birthday

Summary: Multiscale modeling, theory, and computation have made fundamental contributions to many areas of physical, chemical, and biological sciences. Recent theoretical and experimental advances present new challenges for multiscale theory and computation. This conference will seek to stimulate new approaches and collaborations by bringing together both senior and junior researchers with expertise spanning molecular to continuum scales and stochastic to deterministic methods.

Some examples of talks of possible interest to Physics on the schedule:
Epitaxially Strained Elastic Films: Quantum Dots and Dislocations
The Problem of Small Temperatures in a Quantum Gas
Multiscale Dynamical Systems
Wandering in Flatland: the Wonders of 2D Materials
"Metastability: a Journey from Stochastic Processes to Semiclassical Analysis
Spin-Diffusions and Diffusive Molecular Dynamics

Register here


Saturday, September 30th 2017
12:00 pm:
School Picnic in Boom Island Park Shelter B

All members of the School and their families are invited to join a picnic at Boom Island Park Shelter B. I will also be sending out another reminder email to the department this week, but figured it couldn't hurt to try and get as much ad space as we can!

You can sign up for the picnic here.


Monday, October 16th 2017
09:00 am:
Live-stream of press conference, followed by Q & A with LIGO members.

LIGO, Virgo, and about 70 observatories will announce new details and discoveries made in the ongoing search for gravitational waves. This will take place at the National Press Club in Washington, D.C, which will be live-streamed.


Thursday, October 19th 2017
09:00 am:
Thesis Defense in Tate 201-20
Speaker: Allison Kennedy, University of Minnesota
Subject: SuperCDMS Prototype Detector Design and Testing
This is the public portion of Ms. Kennedy's thesis defense. Her advisor is Vuk Mandic.

The SuperCDMS test facility at University of Minnesota aids in the detector R&D and characterization of prototype detectors, as part of the scale-up effort for SuperCDMS SNOLAB. This thesis presents the first full ionization and phonon characterization study of a 100 mm diameter, 33 mm thick prototype Ge detector with interleaved phonon and ionization channels. Results indicate that 100 mm diameter, interleaved Ge detectors show potential for use in SuperCDMS SNOLAB.

As part of detector R&D, the Minnesota test facility also looks beyond the next stage of SuperCDMS, investigating larger individual detectors as a means to easily scale up the sensitive mass of future searches. This thesis presents the design and initial testing results of a prototype 150 mm diameter, 33 mm thick silicon ionization detector. The detector was operated with contact-free ionization electrodes to minimize bias leakage currents, which can limit operation at high bias voltages. The results show promise for the operation of both large volume silicon detectors and contact-free ionization electrodes for scaling up detector mass and bias.

11:00 am:
Special Seminar in B50 Tate
Speaker: Andrew Matas, University of Minnesota
Subject: Implications of LIGO announcements

Thursday, October 26th 2017
10:30 am:
Thesis Defense in 110 PAN
Speaker: Qianhui Shi, University of Minnesota
Subject: Magneto-transport in quantum Hall systems at high Landau levels
This is the public portion of Ms. Shi's thesis defense. Her advisor is Michael Zudov.

Thursday, November 9th 2017
09:00 am:
Thesis Defense in Tate 201-20
Speaker: Chris Conklin, University of Minnesota
Subject: Electrokinetic Phenomena and Singularity-Driven Flows in Nematic Liquid Crystals
This is the public portion of Mr. Conklin's thesis defense. His advisor is Jorge Vinals.

Electrokinetic phenomena, including electrophoresis and electroosmosis, provide a significant tool for engineering the transport of fluids and particles at microscopic scales. This thesis describes additional mechanisms for generating electrokinetic flow by using a nematic liquid crystal electrolyte. Under an applied electric field the anisotropic properties of the liquid crystal lead to separation of ionic impurities present in the fluid, which couple with the applied field to produce electrostatic forces that drive fluid and particle motion. This force is quadratic in the electric field, implying that systematic flow occurs even in the presence of an oscillating field. This thesis presents numerical and analytical investigations of this electrokinetic mechanism. We show that the charge density and fluid velocity of a system depends strongly on the topology of the liquid crystal orientation, and we present results for several distinct configurations, including periodic distortions, isolated disclinations, and particle suspensions. We also show that liquid crystal electrokinetic systems can be designed to mimic the behaviors of active nematics -- collections of particles which can self-propel along a particular direction.


Thursday, November 16th 2017
4:30 pm:
Climate and Diversity Meet and Greet in Tate Hall, Church Street Lobby
Subject: Introduction and Information gathering session
Refreshments will be served.

Join us after the Physics Colloquium for a chance to:

Meet the committee
Find out what we're doing and how we can serve you
Give us feedback and suggestions
Get FREE FOOD (in addition to colloquium cookies)

What you'll find at our tables:

Topic 1: Resources
This table will describe some of the resources available to faculty, researchers, staff, and students campus-wide and within our own School. Stop by and take a handout or fill out a survey, and get to know the members of the School’s Climate and Diversity Committee.

Topic 2: School of Physics and Astronomy climate
These tables will solicit feedback from graduate students on climate issues within the school and describe our upcoming poster campaign.
We will also have representatives from WIPA, GradPhi, SPS, and WISE to provide information about their events and organizations and ways that they provide support.

Topic 3: Inclusiveness
This table will provide information on workshops, training programs, and involvement opportunities available to help all members of the community to better understand and support each other.

Climate and Diversity Website: http://climate-diversity.physics.umn.edu/


Wednesday, November 29th 2017
7:00 pm:
Speaker: Philip Kim, Harvard University
Subject: Stacking atomic layers: quest for new materials and physics
Refreshments in atrium after the lecture .

Modern electronics has been heavily relied on the technology to confine electrons in the interface layers of semiconductors. In recent years, scientists discovered that various atomically thin materials including graphene, a single atomic carbon layer, can be isolated. In these atomically thin materials, quantum physics allows electrons to move only in an effective 2-dimensional (2D) space. By stacking these 2D quantum materials, one can also create atomic-scale heterostructures with a wide variety of electronic and optical properties. I will discuss the creation of new heterostructures based on atomically thin materials and emerging new physics with technological implications therein.


Monday, December 4th 2017
1:00 pm:
Thesis Defense in Akerman 317
Speaker: Sheng Tian, University of Minnesota
Subject: The flow of Poynting flux into the terrestrial cusp and auroral zone and its role in powering energy intensive collisionless acceleration mechanisms
This is the public portion of Mr Tian's thesis defense. His advisor is John Wygant.

Tuesday, December 12th 2017
2:00 pm:
Thesis Defense in PAN 110
Speaker: Ziran Wang, University of Minnesota
Subject: Magnetism for Data Storage: Magnetoresistance Enhancement by Wave Vector Filtering and Transition Shifts in HAMR
This is the public portion of Mr. Wang's thesis defense. His advisor is Randall Victora.

Magnetoresistive heterostructures have important applications in magnetic storage technology and spintronics. This thesis uses Green’s function techniques to calculate the transport properties of a novel structure Fe/Ag/Fe/InAs/Ag. We show that the magnetoresistance can be enhanced to above 1000% due to the wave-vector filtering effect imposed by the InAs layer; meanwhile, the resistance-area product is as low as ~10Ωµm^2. The magnetoresistance shows oscillations with the InAs thickness when the Fermi level is in the conduction band, and the oscillations are quantitatively explained by theory.
Heat-assisted magnetic recording (HAMR) is a leading technology for the next-generation magnetic data storage. This thesis uses micromagnetic simulations to study magnetization transition shifts induced by nonequilibrium spin dynamics in HAMR. We examine the effects of thermal profile, head velocity, damping, and head field rise-time. We also propose methods to determine spin temperature and its lag relative to lattice temperature. By quantifying switching time, spin temperature lag, and superparamagnetic writing, we show that superparamagnetic effects cause largest transition shifts and dominate in typical HAMR processes.


Wednesday, December 13th 2017
09:05 am:

Aaron Durgin & Chase McCabe, "Moessbauer Spectroscopy of Fe57 Compounds"

Jarod White, "NMR Spectroscopy"

Pedro Angulo-Umana & Kai Wang, "Optical Whispering Gallery Mode Resonances"

Jacob Christy & Mitchell Frand, "Single Photon Quantum Interference"


Friday, December 15th 2017
4:00 pm:
Thesis Defense in 110 PAN
Speaker: Sean Kalafut, University of Minnesota
Subject: Search for a WR boson and heavy neutrinos using the LHC and the CMS experiment
This is the public portion of Mr. Kalafut's Thesis Defense. His advisor is Roger Rusack.

Tuesday, December 19th 2017
11:00 am:
Thesis Defense in 110 PAN
Speaker: Gordon Stecklein, University of Minnesota
Subject: Generation and Absorption of Pure Spin Currents Using Graphene Nonlocal Spin Valves
This is the public portion of Mr. Stecklein's thesis defense. His advisor is Paul Crowell.

In this talk I will discuss the fabrication and measurement of nanoscale devices in which a spin-polarized electrical current is used to inject spins into graphene, which then diffuse. We demonstrate the electrical detection of spins in graphene devices with micron-scale spin diffusion lengths and analyze how the spin lifetime and spin diffusion lengths are affected by electrostatic gating. The spin current absorbed by an adjacent ferromagnet is calculated and demonstrated to increase as the electrical conductance of the graphene/ferromagnet interface is improved. Quantitative modeling, including a finite element model of the spatial distribution of spins and the effect of a thin metallic island, indicates that the absorbed spin current is nearing the regime necessary for future technological applications.

1:00 pm:
Thesis Defense in Tate 201-20
Speaker: Mark Mackey, University of Minnesota
Subject: End-Effects in Diblock Copolymer Melts
This is the the public portion of Mr. Mackey's MS Thesis defense.

Friday, December 29th 2017
2:00 pm:
Thesis Defense in M10 library
Speaker: Pamela Sooriyan, University of Minnesota
Subject: Dose enhancement in bone due to the 16O(γ,n)15O reaction
This is the public portion of Ms. Sooriyan's thesis defense. Her thesis advisor is John Broadhurst.

External beam radiation therapy is the most common option in the treatment of malignant tumors. It mainly uses Bremsstrahlung photons produced when highly accelerated electrons are incident on a target of high atomic number, gamma rays produced by radionuclides, and electrons beams. In the mega-voltage range of photon beams, the dose absorbed by the tumor is primarily by the incident photons losing their energy to the tissues of the tumor by Compton scattering and pair production. Enhancing photonuclear disintegrations offers the possibility of increasing the dose to the tumor (for the same delivered dose) by introducing secondary charged particles in the irradiated region.
The dose delivered by secondary charged particles from the 16O(γ,n)15O reaction in bone was measured in an attempt to explore the feasibility of local dose enhancement due to photo nuclear disintegrations.

For an externally delivered dose of 13 Gray, the additional dose due to positrons was measured to be 0.18 mGray in bone and 0.025 mGray in tissue, using a photon beam that had about 1.3% of photons of energy needed to initiate the 16O(γ,n)15O reaction.

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