project title: Collaboration on the Latest Experimental Results for Nuclear
project leader: Prof. Michael Steiner
access given (in days): 30
access used (in days): 28
local host: Prof. Mikko Paalanen
home institution: Hahn-Meitner Institute, Berlin
country of institution: Germany
starting date (yyyy-mm-dd): 2004-09-01
Lithium metal is a promising candidate to study the interplay between superconductivity and nuclear magnetism. It is known to be superconducting at elevated pressures and in the form of thin quenched condensed films. The YKI group of the LTL has conducted at ultra low temperatures a series of NMR measurements on the nuclear spins of bulk lithium samples. The objective of this project is to analyse these results in order to determine the self-organized ground states of the nuclear system and of the conduction electrons. The results of the analysis will be used in planning of the next generation of experiments either at the LTL or at the Hahn-Meitner Institute.
The results will be published in Journal of Low Temperature Physics in an articled titled "Experiments on Nuclear Ordering and Superconductivity in Lithium". No superconductivity was observed in lithium under zero pressure, although two samples were cooled down to lattice temperatures as low as 100 microKelvin. In the collaboration a nontrivial phase diagram of the low temperature magnetic phases was proposed. The critical temperature was found to be 0.3 microKelvin at zero field. The tentative phase diagram has two characteristically different ordered regions as a function of magnetic field: the one at low fields below 0.2 mT shows clear hysteretic behavior, whereas the other one at higher fields adapts reversibly to the changes in the magnetic field. In conclusion, more experimental work was found to be necessary in order to fully describe the complicated phase diagram.