Qiu Research Group

RESEARCH | MEMBERS | PUBLICATIONS | Postdoc Opening Position 

Background:

Electrons in solids determine most of the materials properties. An electron consists of charge and spin. While the electron charge determines the electronic properties, the alignment of electron spins generates magnetism. It is generally believed that a combination of the electron spin and charge freedoms in solids has a potential of creating new generation spintronics technology.

The removal of the spin degeneracy in magnetic materials leads to an inherent spin-charge correlation. Therefore magnetic nanostructures offer a great opportunity for tailoring the spin and charge properties at the nanometer scale. In fact, research on magnetic nanostructures has been developed rapidly in the last two decades with many exciting discoveries such as oscillatory interlayer coupling and giant magneto resistance (GMR).

Goal:

To develop and realize the scientific and technological potentials of the magnetic nanostructures, it is important to understand: how do the electron spins behave at the nanometer scale? and how to create new types of nanostructures with desired properties? Answering these questions is the ultimate goal of our research.

Experimental Techniques:

Because of the short-ranged magnetic exchange interaction, nanometer sets a critical length scale below which a magnetic system behaves very differently. Thus it is very important to fabricate and characterize magnetic nanostructures at the atomic level. We use state-of-the-art technique of Molecular Beam Epitaxy (MBE) to grow high quality single crystal films with a thickness control at the atomic scale. We currently use the following techniques in our experiments.

Ultra high vaccum systems:

  • Molecular beam epitaxy (MBE)
  • Low energy electron diffraction (LEED)
  • Reflection high energy electron diffraction (RHEED)

Sample device fabrications:

  • Mechanical exfoliation and transfer of van der Waals materials
  • Nanofabrication at the Nanofab, including:
    • photolithography
    • E-beam lithography
    • Ar+ ion etching
    • metal deposition systems
    • wire bonding

In-house magnetic characterizations: 

Synchrotron radiation and electron microscopy at Lawrence Berkeley National Lab (LBNL):

Micromagnetic simulation:

Current Projects:

  • Topological spin textures
  • Time-resolved study of spin dynamics
  • Ferromagnetic/Antiferromagnetic spin frustrations