Tuning Magnetic Ground States of Neutral Dopant Clusters in Semiconductors

In recent years, significant effort has been devoted to realizing high-spin ground states in large but finite sized correlated electronic systems in the itinerant regime. Notable progress in this long-standing search has been achieved through the use of quantum simulators, particularly those based on ultracold atoms and semiconductor quantum dot arrays. Dopants in semiconductors in the insulating phase at densities below the metal-insulator transition are known to interact antiferromagnetically and lead to a low-spin random-singlet like phase [1]. High-spin ground states may be obtained in finite sized neutral clusters at these densities for specific cluster geometries [2]; however, this is limited in scope for direct band gap semiconductors because the coupling between hydrogenic dopants is inherently antiferromagnetic. In this work [3], we demonstrate the possibility of creating cluster geometries with much larger moments in their ground state in n-doped indirect band-gap semiconductors in the insulating regime, specifically ones with conduction band minima at the zone boundary, such as Ge and AlAs. We consider clusters both for two-dimensional and three-dimensional geometries and explore the generalizability of this construction.



[1] R. N. Bhatt and P. A. Lee, Physical Review Letters 48, 344 (1982)

[2] Erik Nielsen and R. N. Bhatt, Physical Review B 82, 195117 (2010).

[3] This work is based in part on Haonan Zhou, senior thesis, Princeton University, May 2013 (advisor: R. N. Bhatt).