High field experiment demonstrates the Fulde superconducting state

In 1964, Prof. Peter Fulde, director of the Max Planck Institute for the Physics of Complex Systems in Dresden, together with Dr. Richard Ferrell published a work on a special state of superconducting materials. Approximately at the same time, two other physicists predicted this state as well, this is now called Fulde-Ferrell-Larkin-Ovchinnikov superconducting state. In 2007, this state was proved experimentally in an organic superconductor for the first time. Scientists from the Dresden High Magnetic Field Laboratory participated in this experiment.



Fulde-Ferrell-Larkin-Ovchinnikov superconducting state

High magnetic fields usually destroy the superconducting state, i.e., each superconducting material transforms into a normal conductor beyond a critical magnetic field. Some materials, however, show a special high-field state between the superconducting and the normal conducting state, which can be described as a hybrid state. Here, parts of the material remain superconductors whereas other parts become normal conductors. This state appears preferably in materials, where conducting layers are separated by insulating layers on the nanoscale. Prof. Peter Fulde described this in 1964 by an oscillating spatial modulation of the superconducting state.


Scientists from Geneva, Braunschweig, Dresden and Osaka/Japan participated in the experiments, which were conducted at the High Magnetic Field Laboratory in Grenoble/France.



J. Wosnitza et. al., Calorimetric Evidence for a Fulde-Ferrell-Larkin-Ovchinnikov Superconducting State in the Layered Organic Superconductor k-(BEDT-TTF)2Cu(NCS)2, in: Physical Review Letters 99, 187002 (2007).