Hokkaido University Research Profiles

Japanese
Nanotechnology / Materials

Clarifying the Physical Constants of Electron Spin Control

Accelerating the research and development of next-generation electronic devices

Among various semiconductor properties, we have quantitatively clarified the previously unknown “spin-orbit interactions” of n-type quantum well structures based on InGaAs semiconductors, including gate voltage dependence. This achievement will be a seed for the development of next-generation spin devices.

Content of research

Existing semiconductor devices operate through the electric charge of electrons. In addition to the electric charge, an electron also has the other property of spin, which is a magnetic property. The electron spin in a solid can be aligned in a certain direction (Fig. 1a) or rotated about a specific axis (Fig. 1bc), depending on the situation. The key to realizing next-generation electronic devices is to control such electron spin in semiconductor devices. In this study, we used indium-, gallium-, and arsenic-based field-effect transistors (Fig. 2) and performed electrical measurements in a cryogenic environment (absolute temperature of 20 mK) using a dilution refrigerator (Fig. 3). In this way, we were able to precisely determine for the first time the spin-orbit interaction coefficient, which is necessary to control electron spin (Fig. 4).

  • Fig. 1 Schematic diagram of spin rotation. (a) No spin rotation, (b) spin rotation in one direction, and (c) spin rotation in the opposite direction to (b).

  • Fig. 2: Field-effect transistor

  • Fig. 3: Dilution chiller used in this study.

  • Fig. 4 Gate voltage dependence of the spin-orbit interaction coefficient we have revealed in this study.
    (a)-(c) correspond to the spin rotation in Fig. 1.

Potential for social implementation

  • ・Field-effect spin transistor
  • ・Quantum computers
  • ・Ultra-low power logic devices
  • ・Next-generation electron spin devices

Appealing points to industry and local governments

The spin-orbit interaction coefficient is a measure of the ease with which electron spin can be controlled and manipulated using gates, but its exact value in any semiconductor used to be unknown. This achievement will make it possible to apply semiconductor engineering methods to the future development of devices such as those listed on the left, which will lead to a significant reduction in the cost and time required for device development.

2022/5/27Released