Nanoscale, phonon-coupled calorimetry with sub-attojoule/Kelvin resolution.
We have developed an ultrasensitive nanoscale calorimeter that enables heat capacity measurements upon minute, externally affixed (phonon-coupled) samples at low temperatures. For a 5 s measurement at 2 K, we demonstrate an unprecedented resolution of DeltaC approximately 0.5 aJ/K ( approximately 36 000 k(B)). This sensitivity is sufficient to enable heat capacity measurements upon zeptomole-scale samples or upon adsorbates with sub-monolayer coverage across the minute cross sections of these devices. We describe the fabrication and operation of these devices and demonstrate their sensitivity by measuring an adsorbed (4)He film with optimum resolution of approximately 3 x 10(-5) monolayers upon an active surface area of only approximately 1.2 x 10(-9) m(2).
Fon
W Chung
WC
Condensed Matter Physics, California Institute of Technology 114-36, Pasadena, CA 91125, USA.
Schwab
Keith C
KC
Worlock
John M
JM
Roukes
Michael L
ML