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Supercurrent pumping in Josephson junctions with a half-metallic ferromagnet.
S Takahashi1, S Hikino, M Mori
1Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan.
Physical Review Letters
|October 13, 2007
Summary
This study explores Josephson currents in half-metallic ferromagnets. It reveals how spin dynamics and magnon excitation enable supercurrent flow and proposes a novel supercurrent pumping mechanism.
Area of Science:
- Condensed Matter Physics
- Spintronics
- Superconductivity
Background:
- Josephson junctions are fundamental to superconductivity.
- Half-metallic ferromagnets offer unique spin properties.
- Understanding spin-superconductor interactions is key for novel electronic devices.
Purpose of the Study:
- To theoretically investigate Josephson current in a half-metallic ferromagnet sandwiched between superconductors.
- To elucidate the role of spin dynamics, specifically magnon excitation, in this system.
- To propose a new method for controlling supercurrent via magnetization dynamics.
Main Methods:
- Theoretical modeling of Josephson current.
- Analysis of spin-singlet and spin-triplet Cooper pair conversion.
- Investigation of composite states involving triplet Cooper pairs and magnons.
- Proposal of microwave-driven supercurrent pumping.
Main Results:
- Spin dynamics and magnon excitation are critical for Cooper pair conversion and Josephson current.
- A composite state of triplet Cooper pairs and magnons facilitates supercurrent flow.
- Coherent magnetization precession can drive supercurrent pumping.
Conclusions:
- The interplay of spin dynamics and superconductivity is crucial in half-metallic ferromagnets.
- Magnon-assisted Josephson currents offer new avenues for superconducting spintronics.
- Supercurrent pumping via ferromagnetic resonance presents a tunable control mechanism.
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