Discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP

TL;DR

This study reports the discovery of ferromagnetism with large magnetic anisotropy in ZrMnP and HfMnP single crystals, highlighting their potential for magnetic applications without rare-earth elements.

Contribution

The paper presents the synthesis, characterization, and theoretical analysis of ZrMnP and HfMnP, revealing their ferromagnetic properties and large magnetic anisotropy driven mainly by Mn atoms.

Findings

Curie temperatures around 370 K and 320 K

Large magnetic anisotropy fields (~4.6 T and ~10 T)

First-principles calculations agree with experimental magnetization and anisotropy

Abstract

ZrMnP and HfMnP single crystals are grown by a self-flux growth technique and structural as well as temperature dependent magnetic and transport properties are studied. Both compounds have an orthorhombic crystal structure. ZrMnP and HfMnP are ferromagnetic with Curie temperatures around $370$~K and $320$~K respectively. The spontaneous magnetizations of ZrMnP and HfMnP are determined to be $1.9$~$\mu_\textrm{B}$/f.u. and $2.1$~$\mu_\textrm{B}$/f.u. respectively at $50$~K. The magnetocaloric effect of ZrMnP in term of entropy change ($\Delta S$) is estimated to be $-6.7$ kJm$^{-3}$K$^{-1}$ around $369$~K. The easy axis of magnetization is [100] for both compounds, with a small anisotropy relative to the [010] axis. At $50$~K, the anisotropy field along the [001] axis is $\sim4.6$~T for ZrMnP and $\sim10$~T for HfMnP. Such large magnetic anisotropy is remarkable considering the absence of rare-earth elements in these compounds. The first principle calculation correctly predicts the magnetization and hard axis orientation for both compounds, and predicts the experimental HfMnP anisotropy field within 25 percent. More importantly, our calculations suggest that the large magnetic anisotropy comes primarily from the Mn atoms suggesting that similarly large anisotropies may be found in other 3d transition metal compounds.