Scanning tunnelling microscopy of cleaved bismuth surfaces at low temperatures revealed the existence of identical thin twin interlayers, embedded in the main crystal. The interlayers were strictly ordered along the surface atomic rows. They were of the macroscopic lengths of the order of one micrometre. The width of interlayers was about ∼ 70 Å. It corresponds nearly to the distance at which the height gained due to the tilt of twin interlayer atomic lattice with respect to the main crystal surface reaches the interplanar spacing in the [0001] direction, i.e. ∼ 2 Å. Hence the width "quantization" is connected with the matching of atomic planes at both sides of twin interlayer.

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STM studies of silicon MOS structures and heterostructures based on GaAs at ambient conditions are made. Both an opened surface of the structure (for MOS structure) and the cleaved surface across the structure are investigated. It is concluded that the etching of silicon in HF for several minutes does not result in an increase in average surface roughness. Using the difference in the current–voltage dependence of tunneling gap for a multilayer structure an image of all the layers composing the structure can be obtained without a complicated cleaning of the surface or disruption of the structure.

A sample of quasi-two-dimensional graphite (QTDG) whose magnetic properties are described within the Dirac fermion model is investigated by the nuclear magnetic resonance (NMR) and scanning tunneling microscopy (STM) techniques. The broad spectrum of the sample points to a large dispersion of crystallite sizes in this system, which is also confirmed by STM data. It is established that the local diamagnetic susceptibility may substantially exceed the average value over the sample and reaches an abnormally high value of −1.3 × 10 −4 emu/g at T = 4.2 K, which is greater than the corresponding value of highly oriented graphite by a factor of four.Today there is a large number of publications on the study of transport properties of graphene (see, for example, the review [1]); however, there is quite limited experimen- * e-mail: nikolaev@kapitza.ras.ru tal information on the magnetic properties of graphene. This is associated, first of all, with the extremely small mass of a graphene sheet, which complicates the direct measurement of its magnetization, as well as with other factors. For example, in [2], the authors measured the magnetization of a sample consisting of a large number of isolated graphene sheets by a SQUID magnetometer; however, they failed to correctly determine the proper diamagnetic susceptibility of graphene at low temperatures because of a large paramagnetic contribution of localized magnetic moments. The application of local techniques, such as NMR, is hampered, in addition to the sensitivity problem, by the fact that the demagnetization factor for a magnetic field directed perpendicular to the plane of a sheet for such a plane object as the graphene sheet is equal to unity, which leads to the full compensation of the sample magnetization contribution to the local field. At the same time, for a rather long time, there has been known a carbon material such as quasitwo-dimensional graphite (QTDG) [3,4], which exists in the form of large bulk samples and 1 provides insight into the magnetic properties of graphene. In [4], the author established that the susceptibility of the best samples of QTDG along the c axis amounts to −7.5×10 −5 emu/g at T = 4.2 K, which is a record value after superconductors. In this paper, the author also showed that the temperature dependence of χ c in a wide range of temperatures can be rather well described by the formula for an isolated graphene plane, which was first proposed by McClure [5] and was modified with regard to the broadening of the linear energy spectrum near the Dirac point due to the electron scattering by structural defects.In contrast to single-crystal graphite and highly oriented graphite, QTDG shows no azimuthal ordering of layers along the c axis [3,4]. The important role of the mutual orientation of carbon layers was confirmed by the calculations of the energy-band structure of multilayer graphene [6,7]. In these works, the authors showed that, in the absence of azimuthal ordering of layers, the samples also exhibit a linear dispersion law, wh...