اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدJosephson junction with magnetic-field tunable ground state
105
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We consider an asymmetric 0-pi Josephson junction consisting of 0 and pi regions of different lengths L_0 and L_pi. As predicted earlier this system can be described by an effective sine-Gordon equation for the spatially averaged phase psi so that the effective current-phase relation of this system includes a emph{negative} second harmonic ~sin(2 psi). If its amplitude is large enough, the ground state of the junction is doubly degenerate psi=pmvarphi, where varphi depends on the amplitudes of the first and second harmonics. We study the behavior of such a junction in an applied magnetic field H and demonstrate that H induces an additional term ~H cos(psi) in the effective current-phase relation. This results in a non-trivial ground state emph{tunable} by magnetic field. The dependence of the critical current on H allows for revealing the ground state experimentally.
قيم البحث
اقرأ أيضاً
We demonstrate experimentally the operation of a deterministic Josephson ratchet with tunable asymmetry. The ratchet is based on a $varphi$ Josephson junction with a ferromagnetic barrier operating in the underdamped regime. The system is probed also
under the action of an additional dc current, which acts as a counter force trying to stop the ratchet. Under these conditions the ratchet works against the counter force, thus producing a non-zero output power. Finally, we estimate the efficiency of the $varphi$ Josephson junction ratchet.
62 -
W. A. C. Passos
, F. M. Araujo-Moreira
, W. A. Ortiz (Grupo den Supercondutividade e Magnetismo
1999
In this work we study the magnetic remanence exhibited by Josephson junction arrays in response to an excitation with an AC magnetic field. The effect, predicted by numerical simulations to occur in a range of temperatures, is clearly seen in our tri
dimensional disordered arrays. We also discuss the influence of the critical current distribution on the temperature interval within which the array develops a magnetic remanence. This effect can be used to determine the critical current distribution of an array.
An extended Josephson junction consists of two superconducting electrodes that are separated by an insulator and it is therefore also a microwave cavity. The superconducting phase difference across the junction determines the supercurrent as well as
its spatial distribution. Both, an external magnetic field and a resonant cavity intrafield produce a spatial modification of the superconducting phase along the junction. The interplay between these two effects leads to interference in the critical current of the junction and allows us to continuously tune the coupling strength between the first cavity mode and the Josephson phase from 1 to -0.5. This enables static and dynamic control over the junction in the ultra-strong coupling regime.
We demonstrate a novel approach to thermometry at the nanoscale exploiting a superconducting weak link. Such a weak link probed with nanosecond current pulses serves as a temperature sensing element and, due to the fast inherent dynamics, is capable
of delivering unprecedented temporal resolution. We employ the thermometer to measure dynamic temperature of electrons in a long superconducting wire relaxing to the bath temperature after application of the heating pulse. Our measurement delivers nanosecond resolution thus providing the proof-of-concept of the fastest-todate all-solid-state thermometry. Our method improves the state-of-the-art temporal resolution of mesoscopic thermometry by at least two orders of magnitude, extending temporal resolution of existing experiments and introducing new possibilities for ultra-sensitive calorimeters and radiation detectors.
The Josephson current in a diffusive superconductor/ferromagnet/superconductor junction with precessing magnetization is calculated within the quasiclassical theory of superconductivity. When the junction is phase-biased, a stationary current (withou
t a.c. component) can flow through it despite the non-equilibrium condition. A large critical current is predicted due to a dynamically induced long range triplet proximity effect. Such effect could be observed in a conventional hybrid device close to the ferromagnetic resonance.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
