Quasi-one-dimensional magnetic interactions and conduction electrons in EuCu₅ and EuAu₅ with the characteristic hexagonal structure

ABSTRACT

We have succeed in growing single crystals of EuCu${}_5$ and EuAu${}_5$ with the hexagonal structure by the Bridgman method. Both compounds are known to be ferromagnets with Curie temperatures $T_{\mathrm{C}}=57$ and 13 K, respectively, and the Eu-4f magnetic moments of EuCu${}_5$ are known to orient along the hexagonal c-axis or the [0001] direction by the Mössbauer experiment. The magnetisations at 2 K in EuCu${}_5$ and EuAu${}_5$ in the present experiment saturate at an extremely low field of 2 kOe for $H\parallel \left[0001\right]$, with a Eu${}^{2+}$-moment of $7{\mu }_{\mathrm{B}}/\mathrm{E}\mathrm{u}$. On the other hand, the hard-axis magnetisations for $H\perp$ [0001] saturate at a high field of 40 kOe. It is also found from the electrical resistivty measurement that the electrical resistivities along the current $J\parallel$ [0001] in EuCu${}_5$ and EuAu${}_5$ are about $10\mu \mathrm{\Omega }\cdot \mathrm{c}\mathrm{m}$ at room temperature, which are compared with the resistivities of $\rho =$30–40$\mu \mathrm{\Omega }\cdot \mathrm{c}\mathrm{m}$ for $J\perp$ [0001]. The quasi-one dimensional conductivities are also characteristic, which were clarified from the de Haas-van Alphen (dHvA) experiment and FLAPW energy band calculation for EuAu${}_5$, revealing the existence of a large plate-like Fermi surface.

KEYWORDS:

• Single crystal growth
• EuCu${}_5$
• EuAu${}_5$
• ferromagnets
• dHvA
• Fermi surfaces

Acknowledgments

The authors are very grateful to Prof. H. Kawamura and Dr. K. Aoyama for helpful discussions. Thanks are also to Prof. M. Brian Maple for stimulating and fruitful discussions on exotic superconductivity and non-Fermi liquid of heavy fermions.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

F. Honda http://orcid.org/0000-0002-9485-7384

Y. Haga http://orcid.org/0000-0002-4605-5117

Additional information

Funding

This work was supported by JSPS KAKENHI [grant numbers JP18H04329, JP17K05547, JP15H05882, JP15H05886, JP15H05884, and JP16K05453].