A Transition from Localized to Strongly Correlated Electron Behavior and Mixed Valence Driven by Physical or Chemical Pressure in ACo<sub>2</sub>As<sub>2</sub> (A = Eu and Ca) [electronic resource].
- Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2016.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages 2,724-2,731 : digital, PDF file
- Additional Creators:
- Oak Ridge National Laboratory
United States. Department of Energy. Office of Basic Energy Sciences
National Science Foundation (U.S.)
United States. Department of Energy. Office of Scientific and Technical Information
- In this paper, we demonstrate that the action of physical pressure, chemical compression, or aliovalent substitution in ACo<sub>2</sub>As<sub>2</sub> (A = Eu and Ca) has a general consequence of causing these antiferromagnetic materials to become ferromagnets. In all cases, the mixed valence triggered at the electropositive A site results in the increase of the Co 3d density of states at the Fermi level. Remarkably, the dramatic alteration of magnetic behavior results from the very minor (<0.15 electron) change in the population of the 3d orbitals. The mixed valence state of Eu observed in the high-pressure (HP) form of EuCo<sub>2</sub>As<sub>2</sub> exhibits a remarkable stability, achieving the average oxidation state of +2.25 at 12.6 GPa. In the case of CaCo<sub>2</sub>As<sub>2</sub>, substituting even 10% of Eu or La into the Ca site causes ferromagnetic ordering of Co moments. Similar to HP-EuCo<sub>2</sub>As<sub>2</sub>, the itinerant 3d ferromagnetism emerges from electronic doping into the Co layer because of chemical compression of Eu sites in Ca<sub>0.9</sub>Eu<sub>0.1</sub>Co<sub>1.91</sub>As<sub>2</sub> or direct electron doping in Ca<sub>0.85</sub>La<sub>0.15</sub>Co<sub>1.89</sub>As<sub>2</sub>. Finally, the results reported herein demonstrate the general possibility of amplifying minor localized electronic effects to achieve major changes in material’s properties via involvement of strongly correlated electrons.
- Published through SciTech Connect.
Journal of the American Chemical Society 138 8 ISSN 0002-7863 AM
Xiaoyan Tan; Gilberto Fabbris; Daniel Haskel; Alexander A. Yaroslavtsev; Huibo Cao; Corey M. Thompson; Kirill Kovnir; Alexey P. Menushenkov; Roman V. Chernikov; V. Ovidiu Garlea; Michael Shatruk.
- Funding Information:
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