Nanoscale physics

Competition of magnetic ordering types within periodic Anderson model for quantum dot array
Yu. Skorenkyy, O. Kramar, L. Didukh, Yu. Dovhopyaty
 Ternopil Ivan Puluj National Technical University, 56 Ruska St, Ternopil-46001, Ukraine. 
E-mail: skorenkyy@tntu.edu.ua

Arrays of nano-sized quantum dots are anticipated to play a central role in a range of breakthrough application, from minimizing energy consumption and providing new effective means of energy harvesting to prospective quantum communication technologies. Experimental techniques of quantum dot arrays (QDA) sinthesizing have dramatically progressed recently. However, theoretical understanding of a collective behaviour of these artificial atom systems lags behind, due to complexity of a model description and large variety of competing magnetic and non-magnetic phases. 
Spin-selective electron transfer mechanism in QDA through application of the oscillating magnetic field and gate voltage control has been proposed very recently [1]. We introduce a generalized model of QDA’s strongly correlated electron system in which magnetic impurity levels are hybridized with conduction band and develop the effective Hamiltonian on basis of configurational representation with Hubbard X-operators describing the localized spin subsystem. Within single-particle Green function technique the energy spectrum of such model is calculated which allows obtaining ground states energies for  magnetic and non-magnetic phases. Comparison of indirect exchange integrals in single-particle energy spectrum give hints for understanding mechanisms of the ordering, generalizing results of the previus studies [2,3]. We suggest further development of the noted mechanism [1] by taking into account magnetic ordering tendencies in QDA and tuning the application of external actions accordingly.

1.	Masuda S., Kuan Yen Tan, Nakahara M. Spin-selective electron transfer in quantum dot array // Phys. Rev. B – 2018. - 97 -045418. 
2.	Kramar O., Didukh L., Skorenkyy Yu. Conditions of ferromagnetic ordering in model with Anderson-Hubbard centers: effective Hamiltonian  // Journal of Physics: Conference Series.- 2012. - 391, N 1 - 012158.
3.	Skorenkyy Yu. et al. Phase diagram of metal-insulator transition in system with Anderson-Hubbard centers // Acta Phys. Pol. A - 2012. - 122 – 532.