Effect of Disorder on Superconducting and Charge Density Wave Order
Prof. Goran Karapetrov
Department of Physics
Drexel University
In the 1970s, Il’ya Mihailovich Lifshits famously described the Fermi surfaces as the stage on which the “drama of the life of the electron” unfolds. If perfect crystalline periodicity provides that “stage”, then disorder acts as the set’s decorations – introducing scenery that defines more intricate parts of the plot.
In this talk, I will present our recent findings on how disorder affects the correlated electronic states.
In the first part, I will discuss the quantum breakdown of superconductivity in TiN disordered thin films. By precisely tuning the morphology of reactively sputtered TiN thin films (~30nm), we systematically correlate the structural evolution with the superconducting properties. Althouth one practical goal is to develop low-loss high kinetic inductance films for quantum circuits and detectors, the underlying physics and materials science governing this behavior reveal remarkably rich and complex interplay.
In the second part, I will focus on the transition from long range to a short-range charge order and its effect on charge density wave dynamics. Using x-ray photon correlation spectroscopy (XPCS), we studied the prototypical transition metal dichalcogenide superconductor CuxTiSe2. We find that disorder induced by copper intercalation triggers substantial CDW dynamics. We observed the CDW phase fluctuation on a timescale of minutes to hours above the nominal transition temperature while the order parameter amplitude remains finite. These long timescale fluctuations prevent the system from reaching the global free energy minimum during cooling, ultimately trapping it in a short-range-ordered metastable state. Our results reveal a novel mechanism of domain formation driven by correlated disorder – one that may actually promote the emergence of superconductivity.
Hosted by Prof. Forró