Bulletin of the American Physical Society
Joint Fall 2017 Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the Society of Physics Students
Volume 62, Number 16
Friday–Saturday, October 20–21, 2017; The University of Texas at Dallas, Richardson, Texas
Session N3: Condensed Matter Physics III |
Hide Abstracts |
Chair: Alex Zakhidov, Texas State Univ. San Marcos Room: DGAC 1.102C |
Saturday, October 21, 2017 2:30PM - 2:42PM |
N3.00001: A Preliminary Study of Frenkel Defects from SuperCDMS Soudan Matthew Stein The next generation of dark matter direct detection experiments will require higher than ever sensitivity to WIMP-nucleon interactions. This can be achieved in part through better backgrounds modeling. During the operation of the SuperCDMS Soudan experiment, $^{210}$Pb sources were used for calibration purposes. Data from these sources present an opportunity to study defect formation in Ge crystals from $^{206}$Pb recoils. We specifically look for Frenkel defects which occur when an atom is displaced from its lattice site and occupies an interstitial site elsewhere in the crystal. The study of these defects can lead to better backgrounds modeling, a new parametrization of the Stillinger-Weber potential, and a possible increase in projected sensitivity for future experiments. Presented here is a preliminary study of Frenkel defects. [Preview Abstract] |
Saturday, October 21, 2017 2:42PM - 2:54PM |
N3.00002: Physical characterization of chemically-doped YFe$_{\mathrm{2}}$Ge$_{\mathrm{2}}$ compounds at different Y, Fe and Ge sites Laxmi Risal, Sheng Li, Bing Lv The discovery of superconductivity in the Fe pnictides in 2008 has triggered intensive research on the superconductivity of so called 122 ThCr$_{\mathrm{2}}$Si$_{\mathrm{2}}$-type AFe$_{\mathrm{2}}$As$_{\mathrm{2}}$ (A$=$alkali or alkaline earth metals) compounds, with many superconductors have been found in the past few years. On the other hand, experimental efforts are also carried out to search for superconductivity in the other non-pnictide systems with the same ThCr$_{\mathrm{2}}$Si$_{\mathrm{2}}$-type structures, i.e. RFe$_{\mathrm{2}}$Ge$_{\mathrm{2\thinspace }}$and RFe$_{\mathrm{2}}$Si$_{\mathrm{2}}$ where R$=$ rare earth elements. Superconductivity with transition temperature (T$_{\mathrm{c}})$ at 1.8K is indeed detected in the YFe$_{\mathrm{2}}$Ge$_{\mathrm{2}}$ through stringent synthesis procedure. Herein, we have carried out systematical doping studies at Y, Fe, and Ge sites, with the aim to further enhance the T$_{\mathrm{c}}$. The detail synthesis, x-ray analysis, electrical transport, and heat capacity measurements will be presented, and the results with potential quantum criticality will be discussed. [Preview Abstract] |
Saturday, October 21, 2017 2:54PM - 3:06PM |
N3.00003: Large Random Telegraph Signal noise in Small Silicon CMOS Transistor Structures Gangyi Hu, Mark Lee, Clint Naquin, Hal Edwards, Kenneth Maggio We report observation of random telegraph signal (RTS) noise with unusual large percentage magnitude in the source-drain current ($I_{DS}$) of very small channel area ($<$0.05 $\mu m^2$) Si metal-oxide-semiconductor field-effect transistors (MOSFETs) at low temperature. The relative current fluctuation magnitude ($\Delta I_{DS}/I_{DS}$) and switching rate have been studied as functions of bias, time, and temperature. RTS is normally explained by fluctuations in both density and mobility due to a single carrier captured or emitted by a trap defect in the gate oxide when biased near the threshold voltage. This mechanism leads to a $\Delta I_{DS}/I_{DS}$ of typically 1-5$\%$ in Si MOSFET structures. We observe a nearly perfect two-level RTS with a $\Delta I_{DS}/I_{DS}$ as high as 70$\%$, while the switching rate gradually decreases over time scales of $\sim$1 hour at 15 K. This result may not be consistent with the trapping and detrapping process of one carrier. We speculate that our observed RTS could be due to a slow irreversible change in trap position that ultimately leads to no carrier being captured by a trap. [Preview Abstract] |
Saturday, October 21, 2017 3:06PM - 3:18PM |
N3.00004: Doping studies and superconductivity in Ru-doped Zr$_{\mathrm{5}}$Ge$_{\mathrm{3}}$ system Xiaoyuan Liu, Sheng Li, Varun Anand, Bing Lv Searching for new superconducting materials with distinct crystal structures has been proven to be fruitful in achieving higher transition temperature T$_{\mathrm{c}}$, as seen in cuprates and Fe pnictides. The hexagonal Mn$_{\mathrm{5}}$Si$_{\mathrm{3}}$-type structure, with a large amount of compounds crystallizing in this structure and similar structural derivatives, will be an ideal model system to search for new superconductors. Herein, we are reporting firstly a new superconductor Zr$_{\mathrm{5}}$Ge$_{\mathrm{2.5}}$Ru$_{\mathrm{0.5}}$ with T$_{\mathrm{c\thinspace }}$\textasciitilde 5.7K from our systematic Ru-doping studies at three selected doping sites for the Zr$_{\mathrm{5}}$Ge$_{\mathrm{3}}$ system. Interestingly, with the same Ru-doping, superconductivity is only selectively induced with doping at Ge site, but remains absent down to 1.8K with doping at Zr site or interstitial site. The bulk superconductivity nature for Ru-doped Zr$_{\mathrm{5}}$Ge$_{\mathrm{2.5}}$Ru$_{\mathrm{0.5}}$ sample has been confirmed from magnetic, electrical transport, and heat capacity measurements. The high upper critical field, enhanced electron correlation, extremely small electron-phonon coupling, have indicated possible unconventional superconductivity in this system. Detailed synthesis and characterization will be presented and discussed. [Preview Abstract] |
Saturday, October 21, 2017 3:18PM - 3:30PM |
N3.00005: Automation and Multiplexing of Picoamp Current Measurements of Single Molecule Devices Nolan King, Kuo-Yao Lin, Jason Slinker Performing precise measurement of current in nanoscale devices presents numerous challenges. Mechanical vibration, electromagnetic noise, and humidity in the atmosphere can each induce leakage current or noise in the measurement of high impedance devices. Additionally, the challenge of fabricating uniform devices makes developing automation difficult. Here, we utilized a silicon substrate equipped with an array of gold contacts to terminate the anode and cathode of numerous single molecule devices, a Keithley 6482 source-meter, a set of micromanipulator probes, and 3 ThorLabs DC controlled servos, along with a custom software solution to automate the acquisition of current measurements in the devices. The use of software controlled motors to reposition the substrate for measurement allowed for the automation of measurements of multiple devices at a time. The use of software controlled measurements allows for the practical acquisition of large sets of data, resulting in better trend analysis than manual measurement. We successfully automated multiple steps in the measurement process, and offer suggestions on further improvements to the cost and time burden of measuring electrical characteristics of nanoscale devices. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700