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Departamento de Física de la Materia Condensada

Seminario: "The magnon cooparon quasiparticle"

The magnon cooparon seminar-img
Ponente
Akashdeep Kamra
Institución de origen
Departamento de Física de la Materia Condensada
Fecha
17-02-2023
Hora
12:00
Lugar
Sala de Seminarios del departamento C03 planta 5
Descripción

A superconductor is formed when pairs of electrons undergo condensation into a macroscopically coherent state with a common order parameter. The widely used conventional superconductors are constituted by spin-singlet Cooper pairs. Engineering and controlling exotic spin-triplet Cooper pairs has been a main goal and challenge for the scientific community [1].

In this talk, we will discuss some recent theoretical efforts in achieving the generation and control of such spin-triplet Cooper pairs using magnetic insulators and their spin excitations – magnons. We will show that if the superconductivity is mediated by antiferromagnetic magnons, instead of phonons, the resulting superconducting state is unconventional and can achieve a relatively high critical temperature [2]. Furthermore, unconventional Néel spin-triplet Cooper pairs with pairing amplitude oscillating at atomic length scales have recently been predicted to emerge in antiferromagnet/superconductor bilayers [3]. Finally, we will discuss the emergence of a novel quasiparticle – magnon-cooparon – in a conventional superconductor interfaced with a ferromagnetic insulator [4]. The spatially inhomogeneous exchange field generated by a magnon in the ferromagnet induces spin-triplet Cooper pairs in the adjacent superconductor which act to screen the magnon spin (see the adjacent figure). The magnon-cooparon also enables a powerful magnonic directional coupler, a key element in magnon-based logic and computing paradigms.

References:

[1] Matthias Eschrig. Spin-polarized supercurrents for spintronics: a review of current progress. Rep. Prog. Phys. 78, 104501 (2015).

[2] E. Erlandsen, A. Kamra, A. Brataas, and A. Sudbø. Phys. Rev. B 100, 100503(R) (2019).

[3] G. A. Bobkov, I. V. Bobkova, A. M. Bobkov, and A. Kamra. Phys. Rev. B 106, 144512 (2022).

[4] I. V. Bobkova, A. M. Bobkov, A. Kamra, and W. Belzig. Communications Materials 3, 95 (2022).

Observaciones

Presencial 

(Sala de Seminarios del Departamento C03 planta 5)

Online Ms-Teams

(Seminarios del Departamento FMC)

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