Magnetocaloric Effect.

Description:

The magnetocaloric effect is measured directly by a differential copper – constantan thermocouple, having one junction “sandwiched” within the sample, and another one fixed nearby, and exposed to the same conditions as the sample [1,2].

The temperature range with the current thermocouples is 80 – 360 K. The technique is best suited for magnets A, B, and E.

FEATURES DRESDEN
Local Contact

Yurii Skourski
Catalina Salazar Mejia
Tino Gottschall

Field range 0 ... 60 T
Temperature range 80 ... 360 K
Sample size Typically, two plates with < 4x4 mm², 2 mm height
(other arbitrarily shaped samples can also be accommodated, but two flat surfaces are essential for mounting the thermocouple)
Minimum sample size 1x1x1 mm³
The samples can be mounted with a defined orientation
Sensitivity 0.01 K absolute
Typical experiment Direct adiabatic temperature change ∆Tad (H)
∆Tad as a function of the initial temperature
Field sweep rates can be varied between 200 … 8000 T/s for time-dependent studies of the magnetocaloric effect
rate: < 3 K/min (controlled, typical)
Sample Holder The sample is fixed by using GE varnish. The holder is surrounded by a heater.
Sample environment Vacuum from 375 K down to 80 K
Measurement Examples

(a) Mangetocaloric effect of a Ni-Mn-In Heusler alloy showing time-dependent effect at the first-order transition [3].

(b) The maximum ∆Tad obtained in pulsed magnetic fields compared to other measurement devices from elsewhere.



[1] M. Ghorbani et al., Appl. Phys. Lett. 106, 071904 (2015)
[2] F. Scheibel et al., J. Appl. Phys. 117, 233902 (2015)
[3] T. Gottschall et al., Phys. Rev. Applied 5, 024013 (2016)
local contact: Y. Skourski, C. Salazar Mejia, T. Gottschall