Word and bit line operation of a 1x1 {\mu}m2 superconducting vortex-based memory

TL;DR

This paper experimentally studies vortex-based superconducting memory cells, demonstrating their miniaturization, controllable vortex manipulation through geometrical design, and high-endurance operation at small scales, advancing dense cryogenic memory development.

Contribution

The work introduces a scalable, controllable vortex memory cell with optimized word and bit line operation, achieving high-density, nonvolatile superconducting memory at submicron scale.

Findings

Cells can be miniaturized to submicron sizes.

Asymmetric geometry enables controllable vortex manipulation.

High-endurance, nonvolatile operation at zero magnetic field.

Abstract

The lack of dense random access memory is one of the main bottlenecks for the creation of a digital superconducting computer. In this work we study experimentally vortex-based superconducting memory cells. Three main results are obtained. First, we test scalability and demonstrate that the cells can be straightforwardly miniaturized to submicron sizes. Second, we emphasize the importance of conscious geometrical engineering. In the studied devices we introduce an asymmetric easy track for vortex motion and show that it enables a controllable manipulation of vortex states. Finally, we perform a detailed analysis of word and bit line operation of a 1x1 {\mu}m2 cell. High-endurance, nonvolatile operation at zero magnetic field is reported. Remarkably, we observe that the combined word and bit line threshold current is significantly reduced compared to the bare word-line operation. This could greatly improve the selectivity of individual cell addressing in a multibit RAM. The achieved one square micron area is an important milestone and a significant step forward towards creation of a dense cryogenic memory.