Experiments on Quantum Hall Topological Phases in Ultra Low Temperatures

Technical Report · Sat Feb 14 00:00:00 EST 2015

DOI:https://doi.org/10.2172/1332869· OSTI ID:1332869

Du, Rui-Rui ^[1]

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1. Rice Univ., Houston, TX (United States). Dept. of Physics and Astronomy

This project is to cool electrons in semiconductors to extremely low temperatures and to study new states of matter formed by low-dimensional electrons (or holes). At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures or regular low temperature. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Present studies have been focused on topological phases in the fractional quantum Hall effect in GaAs/AlGaAs semiconductor heterostructures, and the newly discovered (by this group) quantum spin Hall effect in InAs/GaSb materials. This project consists of the following components: 1) Development of efficient sample cooling techniques and electron thermometry: Our goal is to reach 1 mK electron temperature and reasonable determination of electron temperature; 2) Experiments at ultra-low temperatures: Our goal is to understand the energy scale of competing quantum phases, by measuring the temperature-dependence of transport features. Focus will be placed on such issues as the energy gap of the 5/2 state, and those of 12/5 (and possible 13/5); resistive signature of instability near 1/2 at ultra-low temperatures; 3) Measurement of the 5/2 gaps in the limit of small or large Zeeman energies: Our goal is to gain physics insight of 5/2 state at limiting experimental parameters, especially those properties concerning the spin polarization; 4) Experiments on tuning the electron-electron interaction in a screened quantum Hall system: Our goal is to gain understanding of the formation of paired fractional quantum Hall state as the interaction pseudo-potential is being modified by a nearby screening electron layer; 5) Experiments on the quantized helical edge states under a strong magnetic field and ultralow temperatures: our goal is to investigate both the bulk and edge states in a quantum spin Hall insulator under time-reversal symmetry-broken conditions.

• Research Organization: Rice Univ., Houston, TX (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: FG02-06ER46274
• OSTI ID: 1332869
• Report Number(s): DOE-RICE-46274; TRN: US1700742
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
GALLIUM ARSENIDES
SPIN
TOPOLOGY
SYMMETRY BREAKING
ALUMINIUM ARSENIDES
GALLIUM ANTIMONIDES
INDIUM ARSENIDES
TEMPERATURE RANGE 0000-0013 K
ELECTRON-ELECTRON COUPLING
HALL EFFECT
MAGNETIC FIELDS
SPIN ORIENTATION
MATTER
ENERGY GAP
TEMPERATURE DEPENDENCE
ZEEMAN EFFECT
ELECTRONS
COOLING
HOLES
PHASE STUDIES
INSTABILITY
POTENTIALS
NUCLEAR SCREENING
TUNING
T INVARIANCE
Quantum Matter
Low Temperature
Topological Phase