RSS icon
Twitter icon
Facebook icon
Vimeo icon
YouTube icon

Spin Helices in GaAs Quantum Wells and Quantum Wires

February 23, 2015 - 11:00am
Speaker: 
Dominik Zumbuhl
Institution: 
Department of Physics, Uni Basel, Switzerland

This talk will cover two topics. First I will present evidence for helical nuclear spin order in GaAs cleaved edge overgrowth wires. The conductance of the first mode is reduced from 2 e2/h down to 1 e2/h upon lowering temperature from 10 K to below 0.1 K, suggesting lifting of the electron spin
degeneracy in the absence of B. Our results are consistent with theoretical predictions for helical nuclear magnetism in the Luttinger liquid regime.

Second: The spin-orbit (SO) interaction is a crucial resource for spin-based quantum technologies, but also causes spin decay by dephasing and relaxation. In semiconductors, it is possible to protect spins from decay by matching the Rashba and Dresselhaus fields, creating the persistent spin helix state. We report locking of the Rashba and Dresselhaus SO fields to matching strengths while changing both together in this locked state with top and back gates, providing a technique to manipulate spins while keeping them protected from decay. We employ the suppression of weak antilocalization as sensitive detector for matched SO fields, delivering all SO terms when combined with numerical simulations. These techniques are applicable to various semiconductor materials and nanostructures.

2400 Computer and Space Sciences
College Park, MD 20742

Subscribe to A Quantum Bit 

Quantum physics began with revolutionary discoveries in the early twentieth century and continues to be central in today’s physics research. Learn about quantum physics, bit by bit. From definitions to the latest research, this is your portal. Subscribe to receive regular emails from the quantum world. Previous Issues...

Sign Up Now

Sign up to receive A Quantum Bit in your email!

 Have an idea for A Quantum Bit? Submit your suggestions to jqi-comm@umd.edu