• Journal of Semiconductors
  • Vol. 40, Issue 8, 081503 (2019)
Sanghoon Lee1, Sunjae Chung1, Hakjoon Lee1, Xinyu Liu2, M. Dobrowolska2, and J. K. Furdyna2
Author Affiliations
  • 1Department of Physics, Korea University, Seoul 136-701, Korea
  • 2Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA
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    DOI: 10.1088/1674-4926/40/8/081503 Cite this Article
    Sanghoon Lee, Sunjae Chung, Hakjoon Lee, Xinyu Liu, M. Dobrowolska, J. K. Furdyna. Interlayer exchange coupling in (Ga,Mn)As ferromagnetic semiconductor multilayer systems[J]. Journal of Semiconductors, 2019, 40(8): 081503 Copy Citation Text show less

    Abstract

    This paper describes interlayer exchange coupling (IEC) phenomena in ferromagnetic multilayer structures, focusing on the unique IEC features observed in ferromagnetic semiconductor (Ga,Mn)As-based systems. The dependence of IEC on the structural parameters, such as non-magnetic spacer thickness, number of magnetic layers, and carrier density in the systems has been investigated by using magnetotransport measurements. The samples in the series show both a typical anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR)-like effects indicating realization of both ferromagnetic (FM) and antiferromagnetic (AFM) IEC in (Ga,Mn)As-based multilayer structures. The results revealed that the presence of carriers in the non-magnetic spacer is an important factor to realize AFM IEC in this system. The studies further reveal that the IEC occurs over a much longer distance than predicted by current theories, strongly suggesting that the IEC in (Ga,Mn)As-based multilayers is a long-range interaction. Due to the long-range nature of IEC in the (Ga,Mn)As-based systems, the next nearest neighbor (NNN) IEC cannot be ignored and results in multi-step transitions during magnetization reversal that correspond to diverse spin configurations in the system. The strength of NNN IEC was experimentally determined by measuring minor loops that correspond to magnetization flips in specific (Ga,Mn)As layer in the multilayer system.
    $ E\, = \,\sum\limits_{i = 1}^9 {{J_1}({M_i} } {M_{i + 1}}) + \sum\limits_{i = 1}^8 {{J_2}({M_i} } {M_{i + 2}}) - \sum\limits_{i = 1}^{10} {H} {M_i}, $ (1)

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    Sanghoon Lee, Sunjae Chung, Hakjoon Lee, Xinyu Liu, M. Dobrowolska, J. K. Furdyna. Interlayer exchange coupling in (Ga,Mn)As ferromagnetic semiconductor multilayer systems[J]. Journal of Semiconductors, 2019, 40(8): 081503
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