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Search Publications by: Alireza Panna (Fed)

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Displaying 26 - 33 of 33

Designing new structures in epitaxial graphene on SiC: transport and quantum effects

May 13, 2019
Author(s)
Randolph E. Elmquist, Hanbyul Jin, Mattias Kruskopf, Martina Marzano, Dinesh K. Patel, Alireza R. Panna, Albert F. Rigosi
When epitaxial graphene (EG) grows on hexagonal SiC(0001), chemical doping is produced by bonds at the epitaxial interface, or buffer layer. Robust quantum Hall effect (QHE) plateaus are observed at RK/2 = h/2e2, where RK is a constant of electrical

Epitaxial Graphene p-n Junctions

July 9, 2018
Author(s)
Jiuning Hu, Mattias Kruskopf, Yanfei Yang, Bi Y. Wu, Jifa Tian, Alireza R. Panna, Albert F. Rigosi, Hsin Y. Lee, George R. Jones Jr., Marlin E. Kraft, Dean G. Jarrett, Kenji Watanabe, Takashi Taniguchi, Randolph E. Elmquist, David B. Newell
We report the fabrication and measurement of top gated epitaxial graphene p-n junctions where exfoliated hexgonal boron nitride (hBN) is used as the gate dielectric. The four terminal longitudinal resistance across a single junction is well quantized at R_

A Table-Top Graphene Quantized Hall Standard

July 8, 2018
Author(s)
Albert F. Rigosi, Alireza R. Panna, Shamith U. Payagala, George R. Jones Jr., Marlin E. Kraft, Mattias Kruskopf, Bi Y. Wu, Hsin Y. Lee, Yanfei Yang, Dean G. Jarrett, Randolph E. Elmquist, David B. Newell
We report the performance of a quantum standard based on epitaxial graphene maintained in a 5 T table-top cryocooler system. The ν = 2 resistance plateau, with a value of RK-90/2, is used to scale to 1 kΩ, allowing comparisons of the performance of a

Uncertainty of the Ohm Using Cryogenic and Non-Cryogenic Bridges

July 8, 2018
Author(s)
Alireza Panna, Marlin E. Kraft, Albert Rigosi, George R. Jones Jr., Shamith Payagala, Mattias Kruskopf, Dean G. Jarrett, Randolph Elmquist
We describe recent scaling measurements to decade resistance levels based on both cryogenic and non-cryogenic current comparator bridges. National measurement institutes and the International Bureau of Weights and Measures derive traceability for the SI

Construction and Performance of the NIST-4 Magnet System

August 24, 2014
Author(s)
Frank C. Seifert, Alireza R. Panna, Leon S. Chao, Yusi A. Cao, Darine El Haddad, Shisong Li, Stephan Schlamminger, Jon R. Pratt, Heeju Choi, Lori Haley
A watt balance is a promising instrument to realize the unit of mass at the kilogram level. The magnet system is one of the key elements of such an instrument. For the new watt balance currently under construction at the National Institute of Standards and

Construction, Measurement, Shimming, and Performance of the NIST-4 Magnet System

June 6, 2014
Author(s)
Frank Seifert, Alireza Panna, Leon Chao, Bing Han, Shisong Li, Yusi A. Cao, Darine El Haddad, Stephan Schlamminger, Heeju Choi, Lori Haley
The magnet system is one of the key elements of a watt balance. For the new watt balance currently under construction at the National Institute of Standards and Technology a permanent magnet system was chosen. We describe the detailed construction of the