A newly synthesised intermetallic superconductor has so far been grown only as three…
PHYSICS · Multi-part · Fermi University Physics · Condensed Matter, Materials & Soft Matter · Free electrons, energy bands and electronic structure · Free electrons, energy bands and electronic structure
Solid State Physics, Ch The Fermi surface: semiclassical dynamics and its measurement
Problem
A newly synthesised intermetallic superconductor has so far been grown only as three single crystals from the same flux-grown batch, each about 150μm across. Four-probe resistivity on one of them gives a residual resistance ratio RRR=4800 (copper's belly orbit is comfortably resolved in de Haas-van Alphen measurements once RRR≳1000). A field of 1.5T destroys its superconductivity even at the lowest temperatures. The compound crystallises in a cubic Laves-phase structure with three-dimensional metallic bonding throughout and no layered or van der Waals-bonded planes, so no face cleaves flat; the only available surfaces are those left by mechanical polishing. A collaborator has access to a dilution refrigerator, a 15T magnet, a torque magnetometer, a lithographic contacting facility for microcrystals, a UHV photoemission end-station, and time on a positron annihilation (2D-ACAR) spectrometer that needs a single oriented crystal several millimetres across, and asks which of the four Fermi-surface probes, de Haas-van Alphen (dHvA), Shubnikov-de Haas (SdH), angle-resolved photoemission (ARPES) and positron annihilation, could actually be carried out on the three crystals in hand.
((a)) For each of the four techniques, state whether it is feasible with this sample and give the physical reason.
((b)) Recommend a technique to try first, and say what result it would actually give (an area or a full three-dimensional surface).