Dr. Nina Agrinskaya

• We have studied experimentally the ferromagnetic properties of GaAs-AlGaAs quantum wells where the center of GaAs well was doped by Mn while the the neighboring barrier was doped by shallow acceptor Be with an aim to occupy (at least, partially) the states of the upper Hubbard band of Mn acceptors in the well. It was found that while the measurements of the anomalous Hall effect unambiguously demonstrated a presence of ferromagnetic ordering up to rather high temperatures (of 250 K).
• Magnetoresistance of quantum well structures AlGaAs-GaAs, doped by Be, was studied at wide region of magnetic fields up to 10 T for normal and parallel field orientation at temperatures up to 10 K. It was found that at low and moderate magnetic fields magnetoresistance is negative and practically does not depend on field orientation. Then, over broad magnetic field region magnetoresistance is linear in magnetic field. We attribute such a behavior to spin effects. The considerations are presented allowing to explain all the details of the observed physical picture with an account of exchange interactions between localized spins.
• We have studied experimentally transport properties of graphitized silicon carbide controlled by surface graphene layer strongly doped by electrons. At weak magnetic fields and low temperatures a negative magnetoresistance being a consequence of weak localization was observed. We present a first observation in these samples of a crossover in magnetoresistance from weak localization to weak antilocalization (the latter is a manifestation of isospin in graphene). The pronounced picture of Shubnikov – de Haas oscillations was observed at strong magnetic fields (up to 30 T) which demonstrated 4-fold degeneration of carrier spectrum due to double spin degeneration and double valley degeneration. We also observed a manifestation of the Berry phase.

• N.V. Agrinskaya, V.I. Kozub,
  Effect of temperature and magnetic field on disorder in semiconductor structures, J. Exp. Theor. Phys. 124, 311 (2017)
• N.V. Agrinskaya, V.I. Kozub, N.Y. Mikhailin and D.V. Shamshur,
  Spin-controlled negative magnetoresistance resulting from exchange interactions, JETP Lett. 105, 484 (2017)
• N.V. Agrinskaya, V.I. Kozub, N.Y. Mikhailin and D.V. Shamshur,
  Scaling of the breakdown in the impurity band of doped GaAs/AlGaAs quantum well demonstrating virtual Anderson transition, Solid State Commun. 260, 6 (2017)
• N.V. Agrinskaya, V.I. Kozub,
  Ferromagnetism mediated by the upper Hubbard band in selectively doped GaAs/AlGaAs structures, JETP Lett. 102, 222 (2015)
• N.V. Agrinskaya, V.A. Berezovets, A. Bouravlev, V.I. Kozub,
  Ferromagnetic ordering in Mn-doped quantum wells GaAs-AlGaAs resulting from the virtual Anderson transition, Solid State Commun. 183, 27 (2014)

• N.V. Agrinskaya, V.I. Kozub,
  Features of the conductivity and magnetoresistance of doped two-dimensional structures near a metal-insulator transition, JETP Lett. 98, 304 (2013)
• Н.В. Агринская,
  Молекулярная электроника. В книге (сборнике): Молекулярная электроника (111 стр.) 2004 , Изд. СПбГПУ ISBN: 5-7422-0537-6
• N.V. Agrinskaya, T.V. Mashovets,
  Self-compensation in semiconductors: a review dedicated to the hundredth anniversary of the birthday of Y.I.Frenkel, Semiconductors 28, 843 (1994)

• The ferromagnetic properties of GaAs-AlGaAs quantum wells doped by Mn.
• Exchange interactions between localized spins in doped quantum wells near the metal insulator transition.
• Transport properties of graphitized silicon carbide controlled by surface graphene layer.

References (most important)

• N.V. Agrinskaya, V.A. Berezovets, A. Bouravlev, V.I. Kozub,
  Ferromagnetic ordering in Mn-doped quantum wells GaAs-AlGaAs resulting from the virtual Anderson transition, Solid State Commun. 183, 27 (2014)
• N.V. Agrinskaya, V.I. Kozub, A.V. Shumilin, E. Sobko,
  Magnetoresistance in semiconductor structures with hopping conductivity: Effects of random potential and generalization for the case of acceptor states, Phys. Rev. B 82,#075201 (2010)
• N.V. Agrinskaya, V.I. Kozub, D.V. Shamshur, A.V. Shumilin, Y.M. Galperin,
  Slow relaxation of magnetoresistance in AlGaAs-GaAs quantum well structures quenched in a magnetic field, J. Phys.: Condens. Matter 22, #405301 (2010)
• N.V. Agrinskaya, Y.M. Galperin, V.I. Kozub, D.V. Shamshur,
  Anomalous electron transport in doped uncompensated p-GaAs/AlGaAs quantum wells: evidence of virtual Anderson transition, J. Phys.: Condens. Matter 20, #395216 (2008)