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SUMMARY:Unusual magnetoresistance in Ge-Au alloys for low temperature ther
 mometry - Mr James Dann (University of Cambridge\, Semiconductor Physics G
 roup)
DTSTART:20161123T141500Z
DTEND:20161123T151500Z
UID:TALK68975@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:It would be useful to be able to produce thermometers which ca
 n be easily fabricated on devices and which work over a wide range of temp
 eratures\, especially at low temperatures. Such thermometers could be used
  in thermoelectric measurements on a variety of materials\, possibly inclu
 ding the surface states of topological insulators. Ge-Au alloys have been 
 investigated for this purpose. The composition of the alloy and the anneal
 ing conditions have both been varied to investigate how to produce the bes
 t thermometers.\n\nThe resistance has been observed to vary logarithmicall
 y with temperature. This could be explained by the material being composed
  of conducting grains embedded in an insulating matrix. SEM/TEM images see
 m to support this explanation. The logarithmic variation of resistance sho
 uld mean that the material could be useful as a thermometer over a wide ra
 nge of temperatures as desired.\n\nThe magnetoresistance of the Ge-Au allo
 ys exhibits unusual hysteresis. The shape of the magnetoresistance curve d
 epends on the direction in which B is being ramped. There are several poss
 ible explanations for this\, although as of yet no definite conclusions ha
 ve been reached.
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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