Interplay between superconductivity and the Kondo effect on magnetic nanodots

Hyunsoo Yang; Mahn Soo Choi; Grzegorz Ilnicki; Jan Martinek; See Hun Yang; Stuart Parkin

doi:10.1063/5.0046108

Interplay between superconductivity and the Kondo effect on magnetic nanodots

Hyunsoo Yang, Mahn Soo Choi, Grzegorz Ilnicki, Jan Martinek, See Hun Yang, Stuart Parkin

Department of Physics

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

2 Citations (Scopus)

Abstract

We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets.

Original language	English
Article number	152407
Journal	Applied Physics Letters
Volume	118
Issue number	15
DOIs	https://doi.org/10.1063/5.0046108
Publication status	Published - 2021 Apr 12

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/5.0046108

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title = "Interplay between superconductivity and the Kondo effect on magnetic nanodots",

abstract = "We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets. ",

author = "Hyunsoo Yang and Choi, {Mahn Soo} and Grzegorz Ilnicki and Jan Martinek and Yang, {See Hun} and Stuart Parkin",

note = "Funding Information: This research was partly supported by the National Science Centre, Poland, Grant Nos. 2015/17/B/ST3/02799 and 2020/36/C/ ST3/00539. M.-S.C. was supported by the National Research Foundation of Korea (Grant Nos. 2018R1A4A1024157 and 2017R1E1A1A03070681) and the Ministry of Education of Korea (BK21 Four). Publisher Copyright: {\textcopyright} 2021 Author(s).",

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AU - Yang, Hyunsoo

AU - Choi, Mahn Soo

AU - Ilnicki, Grzegorz

AU - Martinek, Jan

AU - Yang, See Hun

AU - Parkin, Stuart

N1 - Funding Information: This research was partly supported by the National Science Centre, Poland, Grant Nos. 2015/17/B/ST3/02799 and 2020/36/C/ ST3/00539. M.-S.C. was supported by the National Research Foundation of Korea (Grant Nos. 2018R1A4A1024157 and 2017R1E1A1A03070681) and the Ministry of Education of Korea (BK21 Four). Publisher Copyright: © 2021 Author(s).

PY - 2021/4/12

Y1 - 2021/4/12

N2 - We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets.

AB - We study the interplay of superconductivity, ferromagnetism, and the Kondo effect in a single system, using vertical geometry and planar magnetic tunnel junction devices, in which a thin CoFe layer is inserted in the middle of the MgO layer, forming a quantum dot like system. It is shown that the Kondo resonance peak at the zero bias coexists with a sharp Bardeen-Cooper-Schrieffer gap on double tunnel junctions, Al/MgO/CoFe nanodot/MgO/Al. It is also found that the competition between superconductivity and the Kondo effect is tunable with magnetic fields and the temperature. The coexistence of Kondo screening and superconductivity survives long range magnetic order in CoFe nanodots with a spin polarization of 0.2; however, it disappears when the CoFe layer becomes a continuous film with a spin polarization of 0.5. The competition between SC and the Kondo effect in the presence of magnetic ordering opens exciting possibilities to control information in nanomagnets.

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Interplay between superconductivity and the Kondo effect on magnetic nanodots

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