Dushko Kuzmanovski

Multiple odd-frequency superconducting states in buckled quantum spin Hall insulators with time-reversal symmetry

We consider a buckled quantum spin Hall insulator (QSHI), such as silicene, proximity coupled to a conventional spin-singlet s-wave superconductor. Even limiting the discussion to the disorder-robu ...

Tuning Majorana zero modes with temperature in π -phase Josephson junctions

We study a superconductor-normal-state-superconductor Josephson junction along the edge of a quantum spin Hall insulator with a superconducting pi phase across the junction. We solve self-consisten ...

Magnetic penetration depth in the presence of a spin-density wave in multiband superconductors at zero temperature

We present a theoretical description of the London penetration depth of a multiband superconductor in the case when both superconducting and spin-density wave orders coexist. We focus on clean systems and zero temperature to emphasize the effect of the two competing orders. Our calculation shows that the superfluid density closely follows the evolution of the superconducting order parameter as doping is increased, saturating to a BCS value in the pure superconducting state. Furthermore, we predict a strong anisotropic in-plane penetration depth induced by the spin-density wave order.

Effect of spin-density wave fluctuations on the specific heat jump in iron pnictides at the superconducting transition

Measurements of the specific heat jump at the onset of superconducting transition in the iron-pnictide compounds revealed strong variation of its magnitude as a function of doping that is peaked near the optimal doping. We show that this behavior is direct manifestation of the coexistence between spin-density-wave and superconducting orders and the peak originates from thermal fluctuations of the spin-density-waves near the end point of the coexistence phase -- a tetracritical point. Thermal fluctuations result in a power-law dependence of the specific heat jump that is stronger than the contribution of mass renormalization due to quantum fluctuations of spin-density-waves in the vicinity of the putative critical point beneath the superconducting dome.

Differential conductance of point contacts between an iron-based superconductor and a normal metal

We present a theoretical description of the differential conductance of point contacts between a normal metal and a multi-band superconductor with extended s\pm pairing symmetry. We demonstrate that the interband impurity scattering broadens the coherent peak near the superconducting gap and significantly reduces its height even at relatively low scattering rates. This broadening is consistent with a number of recent experiments performed for both tunnel junctions and larger diffusive contacts. Our theory helps to better evaluate the energy gap of iron-based superconductors from point contact Andreev spectroscopy measurements.