Spin-precession-assisted supercurrent in a superconducting quantum point contact coupled to a single-molecule magnet

Holmqvist, Cecilia; Belzig, Wolfgang; Fogelström, Mikael

doi:10.1103/physrevb.86.054519

Cited by 14 publications

(24 citation statements)

References 71 publications

(106 reference statements)

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“…In order to understand the supercurrent in ballistic Josephson junctions it is important to analyze the spectral properties of these weak links [22,23]. In a short ballistic superconductor-normal metal-superconductor (S/N/S) junction with equal gaps and at low temperatures, tunneling through Andreev bound states (ABSs) is the dominant contribution to the Josephson current [24].…”

mentioning

confidence: 99%

Andreev spectrum of a Josephson junction with spin-split superconductors

Bujnowski¹,

Bercioux²,

Konschelle³

et al. 2016

EPL

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-The Andreev bound states and charge transport in a Josephson junction between two superconductors with intrinsic exchange fields are studied. We find that for a parallel configuration of the exchange fields in the superconductors the discrete spectrum consists of two pairs of spinsplit states. The Josephson current in this case is mainly carried by bound states. In contrast, for the antiparallel configuration we find that there is no spin-splitting of the bound states and that for phase differences smaller than certain critical value there are no bound states at all. Hence the supercurrent is only carried by states in the continuous part of the spectrum. Our predictions can be tested by performing a tunneling spectroscopy of a weak link between two spin-split superconductors.Introduction. -Superconductors with spin-split density of states have attracted particular interest since the pioneering works of Tedrow and Merservey, in which Zeeman splitting in superconductors was used to determine the spin-polarization of ferromagnetic metals [1,2]. Such spin-splitting can be achieved either by applying an external magnetic field or in thin superconducting films in contact with ferromagnetic insulators (FI) at zero field [3,4]. The spin-split density of states found in superconducting films originates from the exchange interaction between the conduction electrons of the superconductor and the large localised magnetic moments of the FI [5]. In order to obtain large spin-splittings, the use of FIs has the advantage of avoiding the application of high magnetic fields. The spectrum of a conventional superconductor in this case shows two BCS-like densities of states shifted by the energy 2h, where h is the effective exchange field induced in the superconductor film. Here we denote them as spin-split superconductors (SS).

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mentioning

confidence: 99%

Andreev spectrum of a Josephson junction with spin-split superconductors

Bujnowski¹,

Bercioux²,

Konschelle³

et al. 2016

EPL

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“…In Refs. [29,30] it has been shown that when the nanomagnet undergoes a precession due to an external magnetic filed the Andreev levels are affected by the dynamics of the nanomagnet's spin. The resultant Andreev levels depend on the tilt angle and precession frequency.…”

Section: Resultsmentioning

confidence: 99%

“…An analytical expression for the energy of Andreev levels in this junction has been provided in Ref. [30], except a term giving rise to the Zeemann splitting which has not been given an explicit expression for it. To give an illustration for the above discussions let us calculate the energy of Andreev levels by neglecting the tilt angle dependence of this term and replacing it by an effective Zeemann splitting.…”

Section: Resultsmentioning

confidence: 99%

“…This effect may be used in the single spin detection. It has been shown that a spin current is generated in the superconducting leads by spin nutation of the molecular nanomagnet [28,29,30,31]. The spin current induces a torque on the spin and changes its dynamics.…”

Section: Discussionmentioning

confidence: 99%

“…The dynamics of the Andreev bound states and their effects on the current flowing through the junction have also been studied in Refs. [29,30,31].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spin nutation effects in molecular nanomagnet–superconductor tunnel junctions

Abouie¹,

Abdollahipour²,

Rostami³

2013

J. Phys.: Condens. Matter

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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.

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Shapiro like steps reveals molecular nanomagnets’ spin dynamics

2015

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We present an accurate way to detect spin dynamics of a nutating molecular nanomagnet by inserting it in a tunnel Josephson junction and studying the current voltage (I-V) characteristic. The spin nutation of the molecular nanomagnet is generated by applying two circularly polarized magnetic fields. We demonstrate that modulation of the Josephson current by the nutation of the molecular nanomagnet's spin appears as a stepwise structure like Shapiro steps in the I-V characteristic of the junction. Width and heights of these Shapiro-like steps are determined by two parameters of the spin nutation, frequency and amplitude of the nutation, which are simply tuned by the applied magnetic fields.

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Spin-precession-assisted supercurrent in a superconducting quantum point contact coupled to a single-molecule magnet

Cited by 14 publications

References 71 publications

Andreev spectrum of a Josephson junction with spin-split superconductors

Andreev spectrum of a Josephson junction with spin-split superconductors

Spin nutation effects in molecular nanomagnet–superconductor tunnel junctions

Shapiro like steps reveals molecular nanomagnets’ spin dynamics

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