A review of mechanomagnetic spectroscopy. Case study: Dy polycrystals

The current state and capabilities of mechanomagnetic spectroscopy (MMS) are reviewed. Such technique, based on the Piezoelectric Ultrasonic Composite Oscillator Technique (PUCOT) has been developed to study the magnetoelastic coupling through the reversible inverse magnetostriction (reversible Villari effect, RVE) over wide ranges of periodic stress, temperature and polarizing magnetic field H. The technique allows one to study also elastic and anelastic properties simultaneously with RVE. Measurements of RVE can be performed as a function of cyclic applied field H(t)=sinωt at constant temperature or as a function of temperature at fixed H. In contrast to other macroscopic techniques, MMS is not based on the measurement of the strain or length of the sample with and without applied field. This important advantage allows us to study very weak magnetoelastic coupling, like in the antiferromagnetic phase of Dy for magnetic fields as low as the Earth's one, which requires an extremely high sensitivity. Based on the Maxwell relation, an algorithm was developed to estimate the direct longitudinal magnetostriction versus H from the RVE.The work was supported by MINECO and FEDER (Project MAT2014-56116-C4-1-R), Spain. MLC acknowledges the support from the MINECO, Spain, through the aid SEIC-2010-00104. SK acknowledges the support from the Government of the Russian Federation (Grant 074-U01) through ITMO Visiting Professorship program