Materials with multifunctional physical properties are crucial for the modern society, especially those which display a strong coupling between magnetic, lattice and polar degrees of freedom [1]. This by far unexploited capability promises new paradigm-shift technologies for cooling technologies, magnetic data storage, high-frequency magnetic devices, spintronics, and micro-electromechanical systems.
Research in this area has already highlighted complex magnetic materials with potential for multifunctional applications, like CdMn2O4 or multiferroic CdCr2S4 or even RCrO3 with orthorhombically distorted perovskite structure.
These systems present very distinct macroscopic properties which in most cases have an origin in subtle differences in microscopic phenomena. Considering these ideas, it becomes desirable to carry out additional investigations, especially with the help of nanoscale characterization techniques to further examine locally the crystallographic, magnetic, and electric structure properties of these systems. In this context, hyperfine methods, such as perturbed angular correlation (PAC) spectroscopy, are of the highest relevance. In fact, information on structural properties, such as lattice transformation and/or distortion, can be extracted by studying hyperfine interactions, e.g. the electric field gradient (EFG) tensor obtained from the nuclear quadrupole hyperfine interaction. Therefore, measurement of these interactions offers a precise method to investigate condensed matter phenomena yielding direct information of the local charge distribution and magnetic hyperfine fields.
We will present the hyperfine technique, PAC and demonstrate its potential as a good source of information for understanding the complex phenomena that solid-state systems present [2,3].
[1] W. Eerenstein, N. D. Mathur, J. F. Scott, Multiferroic and magneto electric materials, Nature 442 (7104) (2006) 759–765. doi:10.1038/nature05023.
[2] G. N. P. Oliveira, A. M. Pereira, A. M. L. Lopes, J. S. Amaral, A. M. dos Santos, Y. Ren, T. M. Mendonça, C. T. Sousa, V. S. Amaral, J. G. Correia, and J. P. Araújo, Physical Review B 86, 224418 (2012).
[3] G. N. P. Oliveira, P. Machado, A. L. Pires, A. M Pereira, J. P. Araújo and A. M. L. Lopes, Journal of Physics and Chemistry of Solids 91, 182-188 (2016).
Paulo Brás, Paulo Silva, Jaime Silva