B9.

Project title: Generation and Detection of Equilibrium Spin Current in Spin Heterostructures

Spintronic devices are actively studied as information processors because the exploitation of the electronís spin degree of freedom instead of the charge degree of freedom is believed to have advantages, such as longer coherent lifetime, faster data processing speed, and lower electric power consumption, as demonstrated by some spin-based devices available in the market such as the giant magnetoresistance (GMR) spin-valve read heads. The key challenges of this field are the generation, manipulation and detection of spin in non-magnetic semiconductors. Various schemes have been proposed to tackle these challenges with different pros and cons. In this project, we study a novel scheme of generation and control of spin current in semiconductors based on the discontinuity of spin space in a spin heterostructure and the application of scheme in spintronic devices. Similar to the Josephson effect, the equilibrium spin current is generated by the phase difference between the spin wavefunctions on the two sides of a junction. This problem is of important practical interest, because a spin current can be generated in a spin heterostructure without any external charge current and voltage and the approach has potential applications in low power spintronic devices.

References:

Nogueira et al  Europhys Lett 67 p620 (2004)
Lee et al Phys Rev B 68 184413 (2003)
J Wang and K S Chan Europhys Lett 75 p.281 (2006)
J Wang and K S Chan Phys Rev B 74 035342 (2006)
J Wang and K S Chan lanl arxiv cond-matt/0609407

Supervisor: Prof K S Chan (apkschan@cityu.edu.hk)

Webpage: http://www.ap.cityu.edu.hk/personal-website/Chan-KS.htm

Nature of Project: Theory and Computer Modelling

Suitable for: M.Phil. or Ph.D.

Prerequisite: a Bachelor Degree in Physics or Electrical Engineering with strong Physics background; strong interest in semiconductor physics theory, many-body transport theory and Greenís function techniques (both equilibrium and non-equilibrium).