ترغب بنشر مسار تعليمي؟ اضغط هنا

Little-Parks Oscillations in a Single Ring in the vicinity of the Superconductor-Insulator Transition

175   0   0.0 ( 0 )
 نشر من قبل Doron Gurovich
 تاريخ النشر 2014
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

We present results of measurements obtained from a mesoscopic ring of a highly disordered superconductor. Superimposed on a smooth magnetoresistance background we find periodic oscillations with a period that is independent of the strength of the magnetic field. The period of the oscillations is consistent with charge transport by Cooper pairs. The oscillations persist unabated for more than 90 periods, through the transition to the insulating phase, up to our highest field of 12 T.



قيم البحث

اقرأ أيضاً

In superconductors, the condensation of Cooper pairs gives rise to fluxoid quantization in discrete units of $Phi_0 = hc / 2e$. The denominator of $2e$ is the signature of electron pairing, which is evidenced by a number of macroscopic quantum phenom ena, such as the Little-Parks effect and the Josephson effect, where the critical temperature or the critical current oscillates in the period of $Phi_0$. Here we report the observation of fractional Little-Parks effect in mesoscopic rings of epitaxial $beta$-Bi$_2$Pd, a topological superconductor. Besides $Phi_0$, novel Little-Parks oscillation periodicities of $2Phi_0$, $3Phi_0$ and $4Phi_0$ are also observed, implying quasiparticles with effective charges being a fraction of a Cooper pair. We show that the fractional Little-Parks effect may be closely related to the fractional Josephson effect, which is a key signature of chiral Majorana edge states.
Within the phenomenological Ginzburg-Landau theory we investigate the phase diagram of a thin superconducting film with ferromagnetic nanoparticles. We study the oscillatory dependence of the critical temperature on an external magnetic field similar to the Little-Parks effect and formation of multiquantum vortex structures. The structure of a superconducting state is studied both analytically and numerically.
93 - I. Tamir , A. Doron , T. Levinson 2017
The magnetic field driven superconductor to insulator transition in thin films was theoretically analyzed via a vortex-charge duality transformation applied to the Hamiltonian. Vortices condensation was conjectured as the underline physical mechanism of the insulating phase. Experimental evidence supported duality symmetry across the magnetic-field driven superconductor to insulator transition in amorphous Indium Oxide films. Counterintuitively, duality symmetry is broken at low temperatures where the insulating phase develops strongly non linear current-voltage characteristics. Here, we follow the breakdown of duality symmetry down to very low temperatures and demonstrate the restoration of duality symmetry out of equilibrium.
The superconductor-insulator transition of ultrathin films of bismuth, grown on liquid helium cooled substrates, has been studied. The transition was tuned by changing both film thickness and perpendicular magnetic field. Assuming that the transition is controlled by a T=0 critical point, a finite size scaling analysis was carried out to determine the correlation length exponent v and the dynamical critical exponent z. The phase diagram and the critical resistance have been studied as a function of film thickness and magnetic field. The results are discussed in terms of bosonic models of the superconductor-insulator transition, as well as the percolation models which predict finite dissipation at T=0.
We provide a microscopic-level derivation of earlier results showing that, in the critical vicinity of the superconductor-to-insulator transition (SIT), disorder and localization become negligible and the structure of the emergent phases is determine d by topological effects arising from the competition between two quantum orders, superconductivity and superinsulation. We find that, around the critical point, the ground state is a composite incompressible quantum fluid of Cooper pairs and vortices coexisting with an intertwined Wigner crystal for the excess (with respect to integer filling) excitations of the two types.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا