Low Temperature Physics: 40, 352 (2014); https://doi.org/10.1063/1.4871748
Fizika Nizkikh Temperatur: Volume 40, Number 4 (April 2014), p. 454-467    ( to contents , go back )

Quantization of the magnetic moment in CdBxF2–x/p-CdF2–QW/CdBxF2–x nanosandwiches

N.T. Bagraev, L.E. Klyachkin

A.F. Ioffe Physico-Technical Institute RAN, 26 Politekhnicheskaja, St.-Petersburg 194021, Russia
E-mail: impurity.dipole@mail.ioffe.ru

V.V. Romanov

Санкт-Петербургский государственный политехнический университет ул. Политехническая, 29, г. Санкт-Петербург, 195251, Россия

A.I. Ryskin

Санкт-Петербургский национальный исследовательский университет информационных технологий, меха-ники и оптики, Кронверкский пр., 49, г. Санкт-Петербург, 197101, Россия
pos Анотація:

Received June 9, 2013

Abstract

Tunneling CV characteristics, temperature and magnetic field dependences of magnetic susceptibility and specific heat of the CdBxF2–x/p-CdF2–QW/CdBxF2–x planar sandwich structures prepared on the surface of the n-type CdF2 crystal are studied to identify the superconducting properties for the CdBxF2–x δ-barriers confining the ultranarrow p-type CdF2 quantum well. The comparative analysis of the CV characteristics and the conductance-voltage dependences measured respectively at temperature values below and above the critical superconducting point is evidence of the interplay between supercurrent quantization and low-dimensional quantization of 2D holes in the ultranarrow p-type CdF2 quantum well. The temperature- and field-dependent static magnetic susceptibility demonstrates high temperature de Haas–van Alphen oscillations in the sandwich-structure CdBxF2–x/p-CdF2–QW/CdBxF2–x, which are measured in weak magnetic fields. The temperature dependences of the de Haas–van Alphen oscillations identifies a small effective mass value of 2D holes that provides a strong field assumption, μB >> 1, under high temperature conditions. It was for the first time that periodic frequency changes and diamagnetic responses of the de Haas–van Alphen oscillations were registered, with increasing temperature, which revealed the synchronious temperature oscillations of sheet density and effective mass of 2D holes as a result of the mesoscopic properties for the δ-barriers. The results obtained are analyzed in the framework of the quantum states of the Bose condensate that are due to the discrete change of the Cooper pair coherence length when the superconducting δ-barriers exhibit a fractal structure.

PACS: 73.50.–h Electronic transport phenomena in thin films;
PACS: 73.23.Ad Ballistic transport.

Key words: Kosevich–Lifshits formula, quantum well, δ-barriers, cadmium fluoride, de Haas–van Alphen oscillations.

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