Colloquium is held at Chemistry-Physics building (CP), 505 Rose street.
Refreshments with the speaker are served at 3:00 pm in CP-179.
A full list of past and upcoming recordings can be found here.
I will talk about, the measurement of little g; Lunar laser ranging (This
year is the 50th anniversary of the Apollo 11 mission to the moon.); and
the measurement of big G, the Newtonian constant of gravitation. I believe
that by extending the reach of our hands & quickening the response of our
eyes, new measurement methods and instrumental capabilities have driven
and implemented much of scientific progress. In my talk I will evidence
the commonality of all precision measurement physics and introduce some
thoughts about doing science. My aim will be for you to carry away from my
talk some new thought, idea, awareness, or perhaps just a saying that you
will want to think about long after I’m gone.
Host : Misha Eides
High energy particle physics seeks to find the fundamental constituents of matter and understand the forces between them. To accomplish this, powerful high energy accelerators are used to probe smallest possible scale along with complex, large scale detectors. With the discovery of the Higgs particle in 2012, which has been sought for over 5 decades and the subsequent measurements of its properties getting closer and closer to that predicted by the Standard Model, it is increasingly important for the field of high energy physics to fully understand the neutrino sector which deviates from the Standard Model. The precision measurements of oscillation properties, the mass hierarchy and the CP phase measurements demand high intensity neutrino beams and large mass detectors. These new facility provide opportunities to search for dark matter which could be produced in the beams and for boosted dark matter which originates from the galactic center. In this talk, I will discuss searches for low mass dark matter at the Deep Underground Neutrino Experiment (DUNE), progress and timeline of the experiment, including the status of its prototype detectors and the potential for early physics at DUNE.
Low dimensional materials constitute an exciting and unusually tunable platform for investigation of correlated states. Here I will present our results on transport measurements of high quality few-layer graphene and black phosphorus devices. In Bernal-stack trilayer grapehne, we observe tunable integer and fractional quantum Hall states, and quantum parity effect at the charge neutrality point. In tetralayer graphene, we have observed a large intrinsic gap at half filling, up to 80 meV, that arises from electronic interactions in rhombohedral stacking, and multiple Lifshitz transitions in Bernal stacking. Lastly, I will discuss our recent observation of robust long distance spin transport through the antiferromagnetic state in graphene.
The advent of nanofabrication has opened new venues for controlling vortex matter, which is responsible for the electro-magnetic response of all applied superconductors. In particular, nano-hole structures with a variety of intriguing patterns have emerged as a versatile platform for controlling and optimizing vortex pinning in superconductors for enhanced critical current. Magnetic field pinning of vortices with meso and nanoscale magnetic structures has also shown great potential for in-situ manipulation of vortex behavior. Here, I will briefly review the vortex response to a variety of nanostructured hole-arrays in superconductors and in particular, demonstrate that a random pattern, an often-overlooked vortex pinning system, can lead to a significant critical current enhancement over a wide magnetic field range. I will also demonstrate the use of ferromagnetic strips on a superconductor to mimic a vortex triode device and lastly, introduce a novel nano-magnetic patterned structure based on artificial spin-ice rules to realize a globally reconfigurable and locally writable magnetic structure that can subsequently be used to control single flux quanta in a superconducting film. The novel ferromagnetic/superconducting hetero-structure enables switchable and reversible rectification effect of the critical current and furthermore, enables the experimental study of geometric frustration in a flux quanta system.
This work was supported by the Department of Energy, Office of Basic Energy Sciences which also funds Argonne’s Center for Nanoscale Materials (CNM) where the nano-and magnetic patterning and morphological analysis were performed.
Host: DeLong
