NANOCALORIMETER FOR HIGH-RESOLUTION MEASUREMENTS OF LOW-TEMPERATURE HEAT-CAPACITIES OF THIN-FILMS AND SINGLE-CRYSTALS

An innovative nanocalorimeter has been developed for measuring specifi c heats of thin films, multilayers (typicalthickness: 1000 Angstrom) a nd single crystals (mass: 1 mu g) in the temperature range of 1.5-20 K . The addenda of the device are as small as 3 nJ/K at 4 K (0.5 nJ/K at 1.5 K), thus samples with a heat capacity of the order of nJ/K at 4 K can be measured. Heat capacity differences as a function of temperatu re or an external magnetic field (5 T) were determined with a resoluti on of Delta C/C similar or equal to 10(-4). This way we have seen heat capacity variations of less than a pJ/K. We present as an example mea surements on very small Mn12O12 acetate single crystals and a measurem ent of a thin superconducting Pb layer. In the latter measurement we c ould evidence via specific heat a finite size effect. (C) 1997 America n Institute of Physics. [S0034-6748(97)01611-0].