Macroscopic quantum phenomena at low temperatures

Projektinformationen

ID Finanzhilfevereinbarung: INTAS-1010-CT93-0045

Startdatum 1 Mai 1994

Enddatum 30 April 1997

Finanziert unter

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Gesamtkosten € 0,00

EU-Beitrag € 80 000,00

Koordiniert durch

Rijksuniversiteit Leiden
Netherlands

Ziel

The purpose of the research is to study aspects of condensed matter at low temperatures. The subject covers quantum systems characterised by their macroscopic quantum effects, like superconductivity of electrons in the high Tc ceramics, strongly correlated electron systems, superfluidity and its effect in the crystallisation of 3He, 4He and their mixtures, and solid deuterium.

The solidification of the superfluid helium at the lowest possible temperature with particular emphasis on 3He which is magnetic and where the formation of facets, steps and kinks should be affected by the direction of the nuclear spins, will be studied. Crystallisation waves are also expected at temperatures around 1 mK in analogy with the discoveries at 1 K in 4He. The research on polarised D2 using high H/T ratios and a cooled CCD camera in order to gain control on the size of the D2 crystallites will be continued. A theory for the superfluid transition of polarised 3He diluted in 4He in two dimensions has been developed to show that it will happen at manageable temperatures. Work will be done towards cooling a monolayer of 5% 3He in 4He on a quartz microbalance in order to observe the superfluid transition, which, in a field of 15 T, should be about 1 mK. It has also been calculated that superfluid 3He rotating at high speeds (100 rad/s or higher) is an interesting system which displays superfluidity in the direction of rotation and behaves like a solid in the transverse directions. This speed is two orders of magnitude higher than what has been achieved with rotating cryostats. A small cell will be levitated at T < 1 mK and rotated at the required speed.

In the domain of superconductivity NMR and SQUID detection will be used to gain information on vortex lattice properties in type II superconductors, to understand the extremely anisotropic behaviour of the vortex lattice. A new tool, the scanning force microscope as well as the tunnelling microscope, will be used to investigate the gap formation and to image the flux lattice. As regards the description of high Tc superconductors in both normal and superconducting states, further calculations will be performed based on the local pair approach (real space pairing). In order to increase knowledge of the normal behavior of high Tc superconductors, similar types of ceramics (NdCeCuO) with low Tc's will be studied, using a high magnetic field to drive the samples normal at millikelvin temperatures. This will confirm theoretical predictions on the electronic spectrum of high Tc superconductors, thus adding to the understanding of the mechanisms responsible for high temperature superconductivity.

Programm/Programme

• IC-INTAS - International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Thema/Themen

• 15 - Condensed Matter Physics

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

Data not available

Koordinator

Rijksuniversiteit Leiden

• EU-Beitrag: Keine Daten
• Adresse: Nieuwsteeg 18 ; 2311 SB Leiden ; Niederlande
• Gesamtkosten: Keine Daten

Beteiligte (1)

Russian Academy of Sciences

Russland

• EU-Beitrag: Keine Daten
• Adresse: 117334 Moscow GSP-1
• Gesamtkosten: Keine Daten