Paper

CaMn\\(_2\\)Al\\(_{10}\\): itinerant Mn magnetism on the verge of ferromagnetic order

W -G Yin, Steinke, Lucia, Simonson, Jack W, Smith, Greg J, Zellman, Shelby, Kistner-Morris, Jedediah J, Aronson, Meigan C, Puri, Akshat

2015

Overview

We report the discovery of \\CMA, a metal with strong magnetic anisotropy and moderate electronic correlations. Magnetization measurements find a Curie-Weiss moment of \\(0.83\\,\\mathrm{\\mu_B}\\)/Mn, significantly reduced from the Hund's rule value, and the magnetic entropy obtained from specific heat measurements is correspondingly small, only \\(\\approx 9\\) \\% of \\(R \\mathrm{ln}\\,2\\). These results imply that the Mn magnetism is highly itinerant, a conclusion supported by density functional theory calculations that find strong Mn-Al hybridization. Consistent with the layered nature of the crystal structure, the magnetic susceptibility \\(\\chi\\) is anisotropic below 20 K, with a maximum ratio of \\(\\chi_{[010]}/\\chi_{[001]}\\approx 3.5\\). A strong power-law divergence \\(\\chi(T)\\sim T^{-1.2}\\) below 20 K implies incipient ferromagnetic order, and an Arrott plot analysis of the magnetization suggests a vanishingly low Curie temperature \\(T_C\\sim 0\\). Our experiments indicate that \\CMA~is a rare example of a Mn-based weak itinerant magnet that is poised on the verge of ferromagnetic order.

• Publisher: Cornell University Library, arXiv.org
• Subject: Aluminum / Correlation analysis / Crystal structure / Curie temperature / Density functional theory / Divergence / Ferromagnetism / Magnetic anisotropy / Magnetic permeability / Magnetism / Magnetization / Manganese