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Magnetic properties of Mn-doped Ge46 and Ba8Ge46 clathrates
Nirmal Ganguli1, K V Shanavas, Indra Dasgupta
1Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Abstract:
We present a detailed study of the magnetic properties of unique cluster assembled solids, namely Mn-doped Ge(46) and Ba(8)Ge(46) clathrates using density functional theory. We find that ferromagnetic ground states may be realized in both compounds when doped with Mn. In Mn(2)Ge(44), ferromagnetism is driven by hybridization-induced negative exchange splitting, a generic mechanism operating in many diluted magnetic semiconductors. However, for Mn-doped Ba(8)Ge(46) clathrates incorporation of conduction electrons via Ba encapsulation results in RKKY-like magnetic interactions between the Mn ions. We show that our results are consistent with the major experimental observations for this system.
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