Advanced Non-Contact Optical Methods for Measuring the Magnetocaloric Effect

Accurate measuring the temperature of materials, especially in high pulsed and alternating magnetic fields, represents a major challenge in magnetic and, in particular, magnetocaloric research. The disadvantages of the used contact temperature sensors (microthermocouples and film thermistors) are: (1) the effect of electromagnetic interference on their indications, which is proportional to the time derivative of the magnetic field, (2) their relatively long response time due to thermal inertia, and (3) the impossibility of accurate measurement temperatures of thin and microstructured samples. The described difficulties can be avoided by using non-contact optical methods for measuring the temperature of magnets in high magnetic fields. In this review, we describe non-contact optical methods for measuring the magnetocaloric effect using known materials as an example, and provide a comparative analysis of the main characteristics of these methods, such as: maximal magnetic field, sampling frequency, time constant and spectral range of the detector, and temperature error and resolution.