Effect of magnons on the 0-π transition in a superconductor/half-metallic ferromagnet/superconductor junction

S. Hikino; S. Takahashi; M. Mori; J. Martinek; S. Maekawa

doi:10.1016/j.physc.2007.04.251

Effect of magnons on the 0-π transition in a superconductor/half-metallic ferromagnet/superconductor junction

S. Hikino, S. Takahashi, M. Mori, J. Martinek, S. Maekawa

Materials Property Division

Research output: Contribution to journal › Article › peer-review

3 Citations (Scopus)

Abstract

We study the Josephson effect in an s-wave superconductor/dirty half-metal/s-wave superconductor (SC/HM/SC) junction by taking account of the spin dynamics due to the magnon excitation in the HM. Using the fourth order perturbation theory for the tunneling Hamiltonian and Green's function method, we formulate the Josephson critical current in a SC/HM/SC junction. In the tunneling process from the SC to the HM and vice versa, we consider the effect of spin flip tunneling due to the magnon excitation at the interface. As a result, it is found that the spin triplet pair correlation propagates into the HM and the Josephson current flows. We find that the Josephson critical current shows the damped oscillation as a function of the thickness of the HM and the 0-π transition occurs. Moreover, we show that the 0-π transition occurs by changing temperature. The 0-π transition results from magnon excitations in the HM. This proposes a new mechanism with respect to the 0-π transition.

Original language	English
Pages (from-to)	198-201
Number of pages	4
Journal	Physica C: Superconductivity and its applications
Volume	463-465
Issue number	SUPPL.
DOIs	https://doi.org/10.1016/j.physc.2007.04.251
Publication status	Published - 2007 Oct 1

Keywords

Ferromagnet
Josephson effect
Nanostructure
Superconductor
Tunnel junction

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Condensed Matter Physics
Energy Engineering and Power Technology
Electrical and Electronic Engineering

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title = "Effect of magnons on the 0-π transition in a superconductor/half-metallic ferromagnet/superconductor junction",

abstract = "We study the Josephson effect in an s-wave superconductor/dirty half-metal/s-wave superconductor (SC/HM/SC) junction by taking account of the spin dynamics due to the magnon excitation in the HM. Using the fourth order perturbation theory for the tunneling Hamiltonian and Green's function method, we formulate the Josephson critical current in a SC/HM/SC junction. In the tunneling process from the SC to the HM and vice versa, we consider the effect of spin flip tunneling due to the magnon excitation at the interface. As a result, it is found that the spin triplet pair correlation propagates into the HM and the Josephson current flows. We find that the Josephson critical current shows the damped oscillation as a function of the thickness of the HM and the 0-π transition occurs. Moreover, we show that the 0-π transition occurs by changing temperature. The 0-π transition results from magnon excitations in the HM. This proposes a new mechanism with respect to the 0-π transition.",

keywords = "Ferromagnet, Josephson effect, Nanostructure, Superconductor, Tunnel junction",

author = "S. Hikino and S. Takahashi and M. Mori and J. Martinek and S. Maekawa",

note = "Funding Information: This work was supported by (a Grant-in-Aid for Scientific Research on Priority Areas and) the Next Generation Supercomputer Project, Nanoscience program, MEXT, Japan and CREST. One of the authors (M.M.) acknowledges support by the 21st Century COE program, Tohoku University, Materials Research Center and Kakenhi Wakate(B) from MEXT. ",

year = "2007",

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doi = "10.1016/j.physc.2007.04.251",

language = "English",

volume = "463-465",

pages = "198--201",

journal = "Physica C: Superconductivity and its Applications",

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TY - JOUR

T1 - Effect of magnons on the 0-π transition in a superconductor/half-metallic ferromagnet/superconductor junction

AU - Hikino, S.

AU - Takahashi, S.

AU - Mori, M.

AU - Martinek, J.

AU - Maekawa, S.

N1 - Funding Information: This work was supported by (a Grant-in-Aid for Scientific Research on Priority Areas and) the Next Generation Supercomputer Project, Nanoscience program, MEXT, Japan and CREST. One of the authors (M.M.) acknowledges support by the 21st Century COE program, Tohoku University, Materials Research Center and Kakenhi Wakate(B) from MEXT.

PY - 2007/10/1

Y1 - 2007/10/1

N2 - We study the Josephson effect in an s-wave superconductor/dirty half-metal/s-wave superconductor (SC/HM/SC) junction by taking account of the spin dynamics due to the magnon excitation in the HM. Using the fourth order perturbation theory for the tunneling Hamiltonian and Green's function method, we formulate the Josephson critical current in a SC/HM/SC junction. In the tunneling process from the SC to the HM and vice versa, we consider the effect of spin flip tunneling due to the magnon excitation at the interface. As a result, it is found that the spin triplet pair correlation propagates into the HM and the Josephson current flows. We find that the Josephson critical current shows the damped oscillation as a function of the thickness of the HM and the 0-π transition occurs. Moreover, we show that the 0-π transition occurs by changing temperature. The 0-π transition results from magnon excitations in the HM. This proposes a new mechanism with respect to the 0-π transition.

AB - We study the Josephson effect in an s-wave superconductor/dirty half-metal/s-wave superconductor (SC/HM/SC) junction by taking account of the spin dynamics due to the magnon excitation in the HM. Using the fourth order perturbation theory for the tunneling Hamiltonian and Green's function method, we formulate the Josephson critical current in a SC/HM/SC junction. In the tunneling process from the SC to the HM and vice versa, we consider the effect of spin flip tunneling due to the magnon excitation at the interface. As a result, it is found that the spin triplet pair correlation propagates into the HM and the Josephson current flows. We find that the Josephson critical current shows the damped oscillation as a function of the thickness of the HM and the 0-π transition occurs. Moreover, we show that the 0-π transition occurs by changing temperature. The 0-π transition results from magnon excitations in the HM. This proposes a new mechanism with respect to the 0-π transition.

KW - Ferromagnet

KW - Josephson effect

KW - Nanostructure

KW - Superconductor

KW - Tunnel junction

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