Prof. Karl K. Berggren
Cryogenic STM Spectrum Functional AFM image
Fascinating collective behaviour and functionality of superconductivity and ferroics at the nanoscale.
Recent Events (6 months):
New PAPER: Universality near the superconducting-to-insulating transition (In press with PRB).
SLIDES of my ASC2014 talk about universality in thin superconducting films.
New PAPER: Ferroic domain pinning due to crystallographic defects, direct observation and analysis (Adv Func Mat).
New PAPER: Programmable high-frequency filter for cellular communication based on engineered ferroic domains (APL).
New PAPER: Signal enhancement of single photon detection obtained with large-area architecture (Opt Exp with Zhao et al)
This page is under construction, please be patient…
Understanding the competition between order and disorder in nature is a major task of sicentists. Such competition conveniently exists in disordered systems, which exhibit a phase transition that is accompanied by a sudden emergence of ordered collective interactions of the participating electrons and ions. Likewise, advances in device miniaturisation pioneer the vibrant common frontier of physics and technology. Such miniaturisation is significant not only to better understand the fundamental underlying mechanisms of solid-state physics, but also to the information and computational revolution and classical, and quantum optics. However, today, we already know that the main strategy of nano-device fabrication–size reduction of larger-scale devices–has approached its end. Hence, alternative strategies are sought. Smart functional systems, such as ferroic and superconducting (SC) materials form a neat platform for nanoscale devices, because at this scale ‘the material is the machine.’ These systems rely on collective interactions of charged particles that emerge at the nanoscale. Therefore, they are expected to advance both our understanding of the order-disorder competition in nature as well as technological breakthroughs. Nano ferroics and superconductors have already been used in technologies ranging from cellular communication through non-volatile memory devices to single photon and thermal detectors. Nevertheless, the elusive onset of ‘collectiveness’ in these systems is still an open question in physics, encumbering also the accomplishment of their technological potential.
My research addresses directly the question: How do collective interactions emerge? Therefore, I am studying the superconducting-to-insulating and pare-ferro transitions at the nanoscale, mainly by means of direct observations. Moreover, my scientific discoveries contribute to technologies, such as non-volatile memory devices, novel RF filters, augmented IR thermal sensors and high-performance single photon detectors.