Colloquia

Colloquium in Physics

The Physics Department is now officially sponsoring a Colloquium with the invitation of various speakers who work in the fields of Physics or Physics - related professions to give seminars on a variety of topics. 

Location: Archer Building Auditorium (Room 108)

 

Jason F Dark
December 2019: Colloquium Speaker
Date:  Friday, 8 November 2019
Time:  3:00 to 4:00 pm
Place: Archer Bldg. Room 108 (Physics Dept.)

Mr. Jason F Dark

Ph. D. Candidate

School of Physics, College of Sciences

Georgia Tech (Georgia Institute of Technology)

 

Increasing the Signal-to-Noise Ratio of Magnetic Tunnel Junctions by Cryogenic Preamplification

            The study of micromagnetics has led to many technological advancements in magnetic storage, magnetic random-access memory (MRAM), and magnetic field sensing. Various techniques exist to measure the magnetization of these particles using superconducting quantum interference devices (SQuIDs), the magneto-optic Kerr effect (MOKE), ferromagnetic microscopy, or electron transport. We use electron transport to measure the tunnel magnetoresistance (TMR) through junctions of small magnetic particles. This talk will present a technique that can increase the bandwidth and signal-to-noise ratio (SNR) of a TMR signal at cryogenic temperatures. We use a high impedance (~1MΩ) magnetic tunnel junction (MTJ) to simulate a small magnetic particle and incorporate cryogenic preamplification to successfully increase the SNR and bandwidth of the TMR signal at 8 K by factors of 6.62 and 3.87, respectively. The experiment also verified a 1/f noise dependence on the magnetic state of an MTJ. The talk will begin with a short review of the applicable results of micromagnetics followed by details of the experimental setup and device fabrication. The results of the experiment will be discussed as well as the direction of future research.

Short Bio:

             Born and raised in Beaumont, TX, Jason Dark attended Lamar University and received dual degrees in Electrical Engineering and Physics in May 2015. He continued his education at Georgia Institute of Technology earning a Master of Science in Physics in August 2016. Currently, Jason is a Ph.D. candidate in the School of Physics at Georgia Tech under the supervision of Dr. Dragomir Davidović. Jason has also received the Department of Energy’s Office of Science Graduate Student Research Award to complete part of his thesis work at Oak Ridge National Laboratory beginning in January 2020.

Dr. Rafael De La Madrid
April 2019: Colloquium Speaker
Date:  Friday, 26 April 2019
Time:  3:00 to 4:00 pm
Place: Archer Bldg. Room 108 (Physics Dept.)

Dr. Rafael de la Madrid

Associate Professor

Physics Department, College of Liberal Arts & Sciences

Lamar University

 

A Tale of Three Drops

In 2009, in a most celebrated paper, Dr. Rafael Tadmor and coworkers reported a very counter-intuitive property of liquids drops sliding on solid surfaces: A liquid drop hanging from a surface is more stuck to the surface than the same drop on top of the surface. In spite of the attention it drew, there is no accepted explanation for this effect. In this talk, I will present a simple experiment that suggests a simple explanation for this effect.

 

Dr. Edwin L. Piner
April 2019: Colloquium Speaker
Date:  Friday, 5 April 2019
Time:  3:00 to 4:00 pm
Place: Archer Bldg. Room 108 (Physics Dept.)

Dr. Edwin L. Piner

Professor

Physics Department & Materials Science, Engineering and Commercialization Program

Texas State University

 

Heterointerface Science of Gallium Nitride / Diamond

The performance potential of Gallium Nitride semiconductor Heterostructure Field Effect Transistors (HFETs) is substantially limited by the ability of the material to spread and extract heat generated by the mobile charge in the two-dimensional electron gas (2DEG) during device operation.  For example, state-of-the-art performance in current generation GaN HFET commercial devices is on the order of 5 W/mm (dimensional scaling with gate periphery) while research results have demonstrated 40 W/mm, but with severely limited lifetime.  The development of a practical solution for reducing the thermal resistance is key to improving operational capability and transitioning research results into commercial applications.  Multiple pathways for realizing practical solutions to incorporate diamond into GaN FET technology have been investigated.  Diamond is the highest thermal conductivity material, although with relatively low heat capacity.  Therefore, solutions in which the diamond can be applied closest to the 2DEG will most fully take advantage of the appealing material properties of diamond and GaN.  The material development aspects of an approach that places diamond directly in contact with the epitaxial GaN material structure will be presented. 

To Learn More about Dr. Piner's Profile: Dr. Edwin L. Piner

To Learn More about the Piner's Research: Piner Research Group

The Piner Research Group is one of three research groups at TETF (Texas Emerging Technology Fund) Laboratories for the Material Sciences, Engineering, and Commercialization Program for the College of Science and Engineering at Texas State University.

Further Resources of interest:

TEFT Laboratories

Material Sciences, Engineering, and Commercialization Program

 

Dr. Carl Blair - Personal Portrait

Dr. Carl Blair, Ph. D.

Laser Interferometer Gravitational-Wave Observatory (LIGO)

Livingston, Louisiana

Carl Blair is a current employee at the LIGO facility in Livingston, Louisiana as a Post - Doc graduate from the California Institute of Technology and executes research into Opto-mechanics and Cosmology. The most recent publication under his name is titled: "Preventing transient parametric instabilities in high power gravitational wave detectors using thermal transient compensation."
October 2018: Colloquium Speaker
Date:  Friday, 5 October 2018
Time:  3:00 to 4:00 pm
Place: Archer Bldg. Room 108 (Physics Dept.)

"One Hundred Years of Gravitational Waves"

              The story that leads to the detection of gravitational waves has many twists and turns. Mistakes, retractions, false claims, and huge disappointments. In this presentation interesting parts of this story that - explain what gravitational waves are, how they are formed and how we detect them - will be highlighted. Gravitational wave detectors have come a long way since the conception of the Boyd-Feynman sticky beads thought experiment of 1957. The intricacies of the Advanced LIGO detectors will be used to describe the core components of contemporary gravitational wave detectors. The incredible transducer that turns the most explosive events in the universe into signals we can interpret via the smallest strain measurements ever achieved. The current detection catalog will be reviewed highlighting the promise of gravitational wave and multi-messenger astronomy. Finally, an imagined future of gravitational wave astronomy will be explored through the light of the proposed A+, Einstein Telescope, LISA and TianQin projects.

 

Lamar News & Events: Colloquia - LIGO Scientific Collaboration Publications

Dr. Carl Blair's Most Recent Publication: Journal of Classical & Quantum Gravity

Anamaria Effler self portrait image.
March 2018: Colloquium Speaker
Date:  Friday, March 23, 2018
Time:  3:00 to 4:00 pm

Anamaria Effler

Staff Scientist at LIGO 
Livingston, Louisiana

Title: The What, Why and How of LIGO: The challenge of gravitational wave detection

Abstract:

In this presentation, I will give a brief introduction as to how gravitational waves arise from the theory of General Relativity and how LIGO came to be the largest project funded solely by the NSF. I will go over a few of the signals seen by LIGO and what they mean for astronomy - we now can see phenomena which were hidden from us before, like the collision and merger of massive black holes. In 2017 the Nobel prize in physics was awarded to three of LIGO's founders: Rainer Weiss, Kip Thorne, and Barry Barish. 

On the other hand, the LIGO instruments themselves are an engineering work of art, one of the most precise measurements ever devised. There are two LIGO detectors, one in Livingston, LA and one in Hanford, WA. They work (as much as possible) in conjunction with Virgo, the French-Italian detector near Pisa, Italy. In order to have seen the signals they've seen, they must be able to measure the difference in their 4 km arms to about 1 in 10,000th the size of a proton! I hope to convince you that such a feat is possible, and explain some of the tricks as well as some of the issues that we've had to face in the process of achieving our current sensitivity.

 

Lamar News & Events: Colloquia - Science of LIGO: Wrinkles in Time

Inaugural Speaker

The inauguration of our Colloquium begins this semester Spring 2018 with a talk by former Lamar Physics Student, Anthony George who graduated with a BS Physics degree here at Lamar in 1988. 
Date: January 26, 2018, 4th Friday
Location: 108 Archer - Physics Building
Time: (3:00 - 4:00) PM

 

For More Information on Mr. Anthony George:

An Entrepreneur's Journey

The Flyer for Mr. George's Talk

Inaugural Speaker