Spin nutation effects in molecular nanomagnet–superconductor tunnel junctions

Abstract

Abstract. We study the spin nutation effects of the molecular nanomagnet on the Josephson current through a superconductor|molecular nanomagnet|superconductor tunnel junction. We explicitly demonstrate that due to the spin nutation of the molecular nanomagnet two oscillatory terms emerge in the ac Josephson current in addition to the conventional ac Josephson current. Some resonances occur in the junction due to the interactions of the transported quasiparticles with the bias voltage and molecular nanomagnet spin dynamics. The appearance of them indicate that the energy exchanged during these interactions is in the range of the superconducting energy gap. We also show that the spin nutation is able to convert the ac Josephson current to a dc one which is interesting for applications.PACS numbers: 74.50.+r, 75.50.Xx, 75.78.-n ‡ These authors have contributed equally to this work.

Shapiro like steps reveals molecular nanomagnets’ spin dynamics

“…14 The effects of molecular nanomagnet's spin nutation on the Josephson current flowing through the Josephson junction has been studied in Ref. 15. It has been shown that the spin nutation of the molecular nanomagnet causes generation of an ac Josephson current through the junction, in addition to the dc one.…”

“…is the real part of the retarded potential which is obtained using the Matsubara Green's functions and analytical continuation 14,15,28 as;…”

“…29,30 When the molecular nanomagnet's spin has a nutational motion, the Andreev bound states energies vary with the tilt angle oscillation which eventuate in the modulation of the Josephson current. 15 Phase dynamics: In order to detect the spin dynamics of a nutating molecular nanomagnet we insert it in a tunnel Josephson junction and investigate the phase dynamics of the junction. The phase dynamics of a tunnel Josephson junction composed of two superconducting leads, having phase difference χ, coupled through a tunnel barrier and subjected to a bias current I is generally described by resistively shunted Josephson junction (RSJ) model.…”