15th International Conference on Muon Spin Rotation, Relaxation and Resonance

Insights into the magnetic ground state of Fe$_2$P from $\mu$SR, NMR and DFT perspectives

O-23

31 Aug 2022, 10:20

20m

Science and Technology Campus, University of Parma

Oral Site calculations Oral contributions

Speaker

Dr Ifeanyi John Onuorah (Department of Mathematical, Physical and Computer Sciences, University of Parma, 43124 Parma, Italy)

Description

Fe$_2$P alloys have been proposed as promising for applications in magnetocaloric refrigeration due to their first-order magnetic transitions coupled to a magnetoelastic transition, which gives rise to a giant magnetocaloric effect in the vicinity of their Curie temperature [1]. The magnetic structure of Fe$_2$P has been investigated and known to order ferromagnetically, with magnetic moments along the c-axis. However, these earlier sparse and often very old literature on Fe$_2$P are characterized by inconsistencies in the quantitative description of the Fe$_1$ magnetic moment size and the presence of helical states below T$_c$.

Here, using a combined effort of two spectroscopic techniques, $\mu$SR and NMR, in addition to DFT calculations, we have accurately characterized the magnetic ground state of Fe$_2$P. We perform zero applied field measurements using both experimental techniques below the ferromagnetic transition T$_C$ = 220 K [2]. Our DFT calculations reproduce the experimental results and further allow us to improve their interpretation. We show a detailed characterization of the microscopic coupling between the electrons and P-nuclei or the muon in Fe$_2$P, which where then utilized to discuss the microscopic origin of the NMR and $\mu$SR resonances. Particularly, the computational predictions allow to identify correctly a previously mis-attributed signal from $^{31}$P nuclei, an information relevant for future experiments. This work completely characterizes the signal of two technique of election for the characterization of magnetic properties, thus providing an important base for further analysis of different alloy compositions.

References
[1] R. Hussain, F. Cugini, S. Baldini, G. Porcari, N. Sarzi Amadè, X. F. Miao, N. H. van Dijk, E. Brück, M. Solzi, R. De Renzi, and G. Allodi, Phys. Rev. B 100, 104439 (2019).
[2]Pietro Bonfà, Muhammad Maikudi Isah, Benjamin A. Frandsen, Ethan J. Gibson, Ekkes Brück, Ifeanyi John Onuorah, Roberto De Renzi, and Giuseppe Allodi. Phys. Rev. Mat. 5, 044411 (2021)