Sketch of the measurement probe. Panel (a) Top feedthrough, clip assembly, and slide seal, panel (b) lower connector and vacuum chamber.
(a) Adiabatic temperature-change probe, (b) CernoxTM bare chip glued on the supporting plate, (c) sketch of the adiabatic temperature-change probe with sample.
Temporal evolution of the magnetic field and effective sweep rate for the two cases: (a) the electromagnet is turned on, (b) the pneumatic actuator places the sample in the high field region of the magnet.
Drawing of the cryostat insert. This attachment allows to control the system temperature in the zero field region.
Direct ΔT ad measurement across the Curie temperature of a Gadolinium sample in μ0ΔH = 1.65 T both switching the field on and off. (Inset) Superimposed magnetic field profile (white triangles) normalized on the maximum expected ΔT ad and the temperature profile obtained taking into account the sensor heat capacity (red thin profile). Yellow circles are the raw data.
ΔT ad vs. temperature for magnetic field change of μ0ΔH = 1.65 T (triangles). This measurement is compared with in-field DSC performed on the same sample for a μ0ΔH = 1.7 T field variation (purple line).
ΔT ad vs. gadolinium sample mass at 292 K for a magnetic field change μ0ΔH = 1.7 T (circles). The expected ΔT ad as deduced from Eq. (1) (red line).
Relative vs. mass for Gadolinium (black) and Ni45Co5Mn30Ga20 Heusler (white). (Inset) Normalized ΔT ad vs. sample/sensor heat capacity ratio. These curves describe the sensitivity of the ΔT ad probe.
Specific heat and MCE (in inset) as measured on a 30 mg piece Ni45Co5Mn30Ga20 Heusler alloy for μ0ΔH = 1.7 T.
Thermomagnetic cycles derived from direct ΔT ad characterization at different frequencies. Figures (a)–(c) show the Gadolinium magnetocaloric behavior for different T h and T c temperatures of the cycle. Figure (d) shows the system temperature relaxation for a controlled asymmetric background temperature.
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