Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 40: Poster Session Correlated Electrons

TT 40.82: Poster

Wednesday, March 13, 2013, 15:00–19:00, Poster D

Development of high frequency measurement methods for Fermi surface studies under high pressure — •Hui Chang, Sven Friedemann, and Malte Grosche — Cavendish Laboratory, J J Thomson Avenue, Cambridge CB3 0HE, UK

The observation of quantum oscillatory phenomena in high magnetic field, for example of the electrical resistivity (Shubnikov-de Haas), can help resolve the electronic structure of challenging materials. Important progress is expected in a number of areas of current interest, when the Fermi surface can be tracked near to or across pressure and field-induced quantum phase transitions. These include Mott metal-insulator transitions, magnetic or charge density wave transitions and the orbitally selective Mott transition - or Kondo volume collapse - discussed in f-electron metals.

High sensitivity measurements at elevated pressures in anvil cells are hindered by the need to make reliable and robust high quality contacts to submillimetre samples. Radio frequency tank oscillator methods based on tunnel diode or proximity detector based circuits offer an attractive alternative, because they avoid the need to make contacts and at the same time offer supreme relative sensitivity. Further simplification is possible by patterning the detection coil onto the high pressure anvils[1]. We present recent progress in developing such contactless methods for use in high pressure cells and illustrate this by test measurements of quantum oscillations in low carrier density materials.
[1] O. P. Welzel and F. M. Grosche, Rev. Sci. Instrum. 82, 033901 (2011)