Western Illinois University: Macomb Campus
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Department of Physics
Altarifi Student Seminar on March 3
Feb 24, 2014
PHYS600 Monday, March 3, 4:00-4:50 pm
Currens Hall 205
All physics faculty and students are invited.
Speaker: Saleh Altarifi
Graduate Student, Physics Department, WIU
Title: "The Superconducting State of Ba(Fe1-x Cox)2As2"
Superconductivity is an interesting phenomenon that has different properties like the loss of electric resistivity and the expulsion of applied magnetic field. These two properties occur when some materials are cooled down below significant temperatures, called critical temperatures. There are different families of superconductors and the iron based superconductor family is one of them. Iron based superconductors show different physical phases like the structural phase transitions and orthorhombic antiferromagnetic phase as they are cooled down. In the seminar, the properties of superconductivity and the superconducting state of Ba(Fe1-xCox)2As2 will be discussed based on a study done by Gordon et al.[R. T. Gordon, et al., Phys. Rev. Lett. 102, 127004 (2009)]. Different samples of Ba(Fe1-xCox)2As2 are studied by measuring the London penetration depth, the rate at which the applied magnetic field is expelled from the interior of the sample. A tunnel diode resonator (TDR), a sensitive LC oscillating circuit powered by a tunnel diode, is used to make the penetration depth measurements. The changes of the penetration depth as a function of temperature are detected by the changes in the TDR frequency. The study shows that the penetration depth has a power law temperature dependence, and the material does not fall into any category of those we know like the s-wave superconductors or d-wave superconductors. Also, during the presentation, the work done in the laboratory and machine shop to build a TDR lab in the Physics department, under the direction of Dr. Gordon, will be presented. Examples of the work done are building a voltage bias box and band pass filter, and writing different software programs using Labview. By building the TDR lab, a new study about Ba(Fe1-xCox)2As2 and others projects will be carried out.