Table of contents

The correlations in the ground state of interacting electrons in a two-dimensional quantum dot in a high magnetic field are known to undergo a qualitative change from liquid-like to crystal-like as the total angular momentum becomes large. We show that the composite-fermion theory provides an excellent account of the states in both regimes. The quantum mechanical formation of composite fermions with a large number of attached vortices automatically generates composite fermion crystallites in finite quantum dots.

We discuss several different techniques for evaluating the Green function for a semi-infinite system using a localized basis. We demonstrate that the different techniques are different ways of calculating the self-energy associated with the surface. They give equivalent results but have different convergence properties.

Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM.

Scanning tunnelling microscopy and core level photoemission spectroscopy experiments demonstrate that an ordered surface reconstruction of Pb, Sn and Si adatoms (1/3 monolayer overall coverage) can be formed with symmetry on the Si(111) substrate. Pb, Sn and Si atomically intermix, occupying T₄ sites as in the case of the well known pure 1/3 ML Sn or Pb reconstructions. The electronic structure of this surface, investigated with scanning tunnelling spectroscopy and valence band photoemission, shows a semiconducting behaviour (0.4 eV bandgap), and two surface bands centred at ± 0.7 eV with respect to the Fermi level. These features are significantly different from those of the electronic structure of the binary Pb–Si/Si(111) and Sn–Si/Si(111) 2D alloys. This occurrence demonstrates that tailoring the electronic structure of a surface alloy is viable just by mixing adatoms with the same valence and different sizes.

The influence of the mismatch effect on thin ferroelectric film properties has been studied in the phenomenological theory framework. The polarization dependent part of the surface energy that defined the boundary conditions for the Euler–Lagrange differential equation was written as a surface tension energy. The latter was expressed via the surface polarization and the tension tensor related to the mismatch of the substrate and film lattice constants and thermal expansion coefficients. The interfacial strain caused by the mismatch effect induces the additional surface polarization P_m via a piezoelectric effect that arises near the surface in any film.

The new parameter P_m/P_S (P_S is the known value of the spontaneous polarization in the bulk ferroelectric material at T = 0 K) appeared in the derived phenomenological equations. So we calculate the influence of the parameter P_m/P_S on the depth distribution of the dimensionless film polarization P/P_S, its dependence on temperature, film thickness and applied electric field, as well as that on the hysteresis loop shape, coercive field values, phase diagram and average dielectric susceptibility temperature dependence. Non-zero P_m/P_S values cause a mismatch induced thickness dependent internal electric field E_m. We have shown that this field drastically influences all the properties. In particular, the polarization profile becomes asymmetrical, the polarization temperature dependence resembles that in the external electric field and there is a possibility of external field screening by the internal field E_m. The asymmetry obtained for the hysteresis loop suggests that it is possible that the self-polarization phenomenon recently observed in some films is related to the mismatch effect. The thickness induced ferroelectric–paraelectric phase transition has been shown to exist when |P_m|/P_S<1. A large enough ratio |P_m|/P_S>1 could be the physical reason for the ferroelectric phase conservation in ultrathin film. The possibility of observing the peculiarities of the film property temperature and thickness dependences related to the mismatch effect is discussed.

The IR-induced second-harmonic generation in PbSe microcrystallites with sizes of 10–30 nm is observed for the first time. A phenomenological approach of the IR picosecond nonlinear optical response in PbSe is developed for the middle-IR spectral range (5–15 µm). A model reproducing the basic features of experimental data related to second-order optical nonlinearity caused by photoinduced electron–phonon anharmonic interactions is proposed. The model is based on the band structure calculations and photoinduced kinetics with account taken of electron–phonon anharmonic interactions.

The structural behaviour of SnS under high-pressure has been investigated by angular dispersive synchrotron powder diffraction up to 38.5 GPa. A structural phase transition from orthorhombic α-SnS to monoclinic γ-SnS was observed at 18.15 GPa. The fit of a Birch–Murnaghan equation-of-state gave the volume at zero pressure of V₀ = 192.6(3) Å³, the bulk modulus at zero pressure of B₀ = 36.6(9) GPa and the pressure derivative of the bulk modulus for α-SnS and V₀ = 160(1) Å, B₀ = 86.0(5) GPa and for γ-SnS. The improper ferro-elastic transition is of first-order and is accompanied by a large volume discontinuity of about 9.1%. The phase transition can be described in terms of a group/subgroup relationship. The doubling of the unit cell indicates a wavevector (1/2,0,1/2) at the U-point in the Brillouin zone.

Single crystals of Zn_1−xMn_xIn₂Se₄ were grown by the chemical vapour phase transport (CVT) technique. Through x-ray powder diffraction patterns and Laue diagrams of single crystals we studied the transformation from the layered rhombohedral structure of Mn In₂Se₄ to the tetragonal structure of Zn In₂Se₄. On the Zn In₂Se₄ side, we observe single-phase, solid solution samples for x = 0.01 and 0.25, as is the case for the Mn In₂Se₄ side with x = 1 and 0.87. For the intermediate concentrations x = 0.35, 0.60 and 0.67 we observe our samples to be two-phase mixtures.

The effect of rapid thermal processing (RTP) on the oxygen precipitation occurring at 1050 °C in a Czochralski (CZ) silicon wafer has been investigated. It has been proved that the RTP-induced vacancies only enhance the early stage oxygen precipitation at 1050 °C in terms of the precipitation rate. Furthermore, it is somewhat unexpected that after a lengthy 1050 °C anneal the oxygen precipitates generated in the CZ silicon wafer with prior RTP treatment had considerably lower density and larger sizes in comparison with those generated in the CZ silicon wafer without prior RTP treatment. The reason for this is that the prior RTP treatment will dissolve some of the grown-in oxygen precipitates, thus making the RTP-treated wafer possess fewer nuclei contributing to oxygen precipitation in the subsequent 1050 °C anneal. Moreover, the numbers of resulting precipitated oxygen atoms due to a lengthy 1050 °C anneal were nearly the same in the CZ silicon wafers with and without prior RTP treatment. Additionally, it has been illustrated that the high temperature RTP has superior capability to dissolve the existing oxygen precipitates. It is worthwhile to point out that, when addressing the effect of RTP on the oxygen precipitation behaviour during the subsequent anneal, two functions arising from the RTP treatment, that is, the injection of vacancies into the silicon wafer and the dissolution of grown-in oxygen precipitates existing in the silicon wafer, should be taken into account.

The pseudocubic lattice parameter of lanthanum molybdate, La₂Mo₂O₉, has been measured as a function of temperature between 13 and 1100 K. These data show an anomaly at 842 K, associated with the alpha (pseudocubic monoclinic, non-conducting) to beta (cubic, conducting) phase transition. For a sample which has been quenched from high temperatures, the a(T) data are continuous across this transition, indicating that the transition is smeared or thermodynamically second order. When the same material is cooled slowly, subsequent measurements show the transition to be first order, with a similar transition temperature. The difference between these two behaviours is attributed to changes in oxygen ordering resulting from different thermal histories.

Epitaxial lift-off (ELO) is a process which allows for the separation of a single crystalline III/V thin film or device from the substrate it was deposited on. This process is based on the selective etching of an intermediate AlAs release layer in an aqueous HF solution. The lateral etch rate of the AlAs release layer through a narrow crevice in the weight-induced epitaxial lift-off (WI-ELO) process is much larger than observed for unobstructed planar AlAs layers. It is possible that this increase in etch rate is caused by the tensile strain induced upon the AlAs layer in the WI-ELO setup. In order to verify this assumption, planar AlAs layers, subjected to a controlled curvature, were etched in HF solutions and their etch duration was measured. The applied curvature reduced the already present compressive strain due to lattice mismatch. For large applied bending radii no change in etch rate was observed, because the induced bending is smaller than the already present bending due to the lattice mismatch. Further bending induces a total compressive strain from −0.126% to −0.11%, resulting in an etch rate variation from 0.054 up to 0.066 mm h⁻¹. Measurements on AlAs layers experiencing a tensile strain of +0.286% showed much higher etch rates of 0.134 mm h⁻¹.

The present results obtained on etching experiments in the lateral plane are extrapolated to the perpendicular direction so that a combination with the data from previous work becomes feasible. This results in a better microscopic picture of the etch front in the WI-ELO process. It is found that the force exerted by the weight can be projected on an area, limited by the sample width and a depth of approximately 6 µm.

An analytical variational method is applied to the molecular Holstein Hamiltonian in which the dispersive features of the dimension dependent phonon spectrum are taken into account by a force constant approach. The crossover between a large and a small size polaron is monitored, in one, two and three dimensions and for different values of the adiabatic parameter, through the behaviour of the effective mass as a function of the electron–phonon coupling. By increasing the strength of the intermolecular forces the crossover becomes smoother and occurs at higher e–ph couplings. These effects are more evident in three dimensions. We show that our modified Lang–Firsov method starts to capture the occurrence of a polaron self-trapping transition when the electron energies become of order of the phonon energies. The self-trapping event persists in the fully adiabatic regime. At the crossover we estimate polaron effective masses of order times the bare band mass according to the dimensionality and the value of the adiabatic parameter. Modified Lang–Firsov polaron masses are substantially reduced in two and three dimensions. There is no self-trapping in the antiadiabatic regime.

Modelling Joule heating is a difficult problem because of the need to introduce correct correlations between the motions of the ions and the electrons. In this paper we analyse three different models of current induced heating (a purely classical model, a fully quantum model and a hybrid model in which the electrons are treated quantum mechanically and the atoms are treated classically). We find that all three models allow for both heating and cooling processes in the presence of a current, and furthermore the purely classical and purely quantum models show remarkable agreement in the limit of high biases. However, the hybrid model in the Ehrenfest approximation tends to suppress heating. Analysis of the equations of motion reveals that this is a consequence of two things: the electrons are being treated as a continuous fluid and the atoms cannot undergo quantum fluctuations. A means for correcting this is suggested.

We have investigated the electrical transport in mesoscopic low-density 2D electron systems as a function of background disorder. At zero magnetic field, over a specific window of disorder and electron density, an unusual density-dependent oscillatory pattern in conductance was observed as the Fermi energy was swept in the localized regime. The temperature, source–drain bias and magnetic field dependence of transport indicate the formation of a pinned electron solid, which undergoes a series of order–disorder transitions as the electron density is changed by a gate.

An investigation of the combined effects due to the electronic interaction, anisotropy and the magnetic field interaction for two-electron quantum dots with harmonic confinement is performed. The electronic level structure and the dynamics of the dot are studied with varying field strength and anisotropy. The magnetization is derived for the complete deformation regime covering the regime of weak to strong fields. The cases without and with inclusion of the spin Zeeman interaction for a GaAs semiconductor are considered. The classical dynamics of the interacting electrons is studied and exhibits near integrability for field strengths leading to ratios ω₁:ω₂ = 1:n.

A systematic study of Mn monomers, dimers, trimers, and wires interacting with an (8, 0) semiconductor single-wall carbon nanotube (SWCN) is presented. Spin-polarized total-energy ab initio calculations based on the density functional theory are used to describe the structural, electronic and magnetic properties of all studied systems. For Mn monomers, either outside or inside the nanotube, the most stable configuration is found to be over the centre of the hexagonal site. The most stable geometry for outside dimers presents the Mn atoms adsorbed directly on top of C atoms, when in a high-spin configuration, whereas for a low-spin configuration the Mn atoms are adsorbed on bond-centred sites at opposite sides of a hexagonal ring, with the Mn–Mn bond aligned in a diagonal direction relative to the tube axis in both cases. There are many low energy configurations (at above the lowest energy ones) at distinct orientations, for both the low and high energy configurations. For trimers, two kinds of Mn structures are investigated: compact or open. The compact trimers are found to be more stable than the open systems by approximately 1 eV/Mn atom. A monoatomic wire in a zig-zag configuration has a binding energy that is intermediate between the open and the compact trimers, independently of the spin configuration. For all the investigated Mn structures adsorbed on the SWCN, either high-spin (HS) or low-spin (LS), the interactions between Mn atoms and between Mn and C atoms become stronger as the Mn coordination number increases. The resulting magnetic moments for all adsorbed systems are found to be close to their original values for the corresponding free Mn structures.

The quantum Hall system in a high Landau level under the influence of a one dimensional spatially periodic potential is investigated by direct diagonalization. We consider the N = 2 Landau level at half filling for finite systems with aspect ratio one. Hence the symmetry breaking, or lack thereof, is due to the periodic potential. In agreement with mean field and perturbation theory studies, direct diagonalization indicates that for weak potentials stripes order perpendicular to the external potential. At stronger values of the potential, the potential dominates and the periodicity seen is determined by the potential and not the stripes. An example is given where randomness tends to enhance the symmetry breaking induced by the periodic potential.

The linear thermal conductance of a quantum point contact displays a half-plateau structure, almost flat regions appearing close to half-integer multiples of the conductance quantum. This structure is investigated for the saddle-potential model; its behaviour as a function of contact parameters is also investigated. Half plateaus appear when the thermal energy is less than the subband separation and greater than the energy scale over which the transmission probability for a subband changes. The effect arises from the presence of a current node in the energy-resolved heat current, an energy at which the current is zero. When the transmission steps cross the current node as the gate voltage is varied, the heat conductance remains constant, creating the half plateaus, and this happens only for a certain temperature range. It is found that with increasing temperature the half plateaus become wider and flatter, which makes them more pronounced. It is also found that no half plateaus are present at the first step for any parameter values, and this is tied to the effect that the current node is pushed above the first step by the strong Seebeck potential.

The paramagnetic limit H_p of the upper critical magnetic field H_c2 in superconductors with charge-density waves has been derived in the framework of the self-consistent approach. The obtained quantity H_p always exceeds the Clogston–Chandrasekhar value H_p^BCS. Relevant experimental data for inorganic and organic superconductors with H_c2> H_p^BCS are analysed and are shown to be in qualitative agreement with the proposed theory.

We report on structural, frequency dependent ac susceptibility, dc magnetization and magnetoresistance (MR) measurements on polycrystalline samples of La_0.86Ca_0.14Mn_1−yCr_yO₃ (y = 0, 0.1 and 0.2) prepared by the sol–gel technique. For y = 0, a paramagnetic to ferromagnetic transition was observed at T_c = 185 K.For y = 0.1, the value of T_c = 200 K, an increase of 15 K, and for y = 0.2, T_c = 195 K,an increase of 10 K. The imaginary part of the ac susceptibility for all three samples shows a secondary transition at T_f< T_c. For y = 0, there is no definite law accounting for the frequency dependence of T_f and it is attributed to a transition arising out of a canted structure. However, in the cases of y = 0.1 and 0.2, the frequency dependence indicates the presence of a re-entrant spin glass transition at T_f. Although all three samples show a semiconducting behaviour between 300 and 5 K, a negative MR was observed corresponding to T_c and T_f. The value of MR decreased for the Cr substituted samples.

We study the interplay of quantum impurity, and collective spinon and holon dynamics in Zn doped high-T_c cuprates in the normal state. The two-dimensional models with one Zn impurity and a small amount of Zn impurity are investigated within a numerical method based on the double-time Green function theory. We study the inhomogeneities of the holon density and antiferromagnetic correlation background in cases with different Zn concentrations, and obtain that doped holes tend to assemble around the Zn impurity with their mobility being reduced. Therefore a bound state of the holon is formed around the nonmagnetic Zn impurity with the effect helping Zn to introduce local antiferromagnetism around itself. The incommensurate peaks we obtained in the spin structure factor indicate that Zn impurities have effects on mixing the q = (π,π) and 0 components in spin excitations.

The microstructure, magnetic and electrical transport properties of La_0.67Sr_0.33MnO₃/Nd_0.67Sr_0.33MnO₃ composites are studied as a function of sintering temperature. At 900 °C, the intergrain exchange couplings between the adjacent particles give rise to an increase in resistance. Raising the sintering temperature induces the formation of an interfacial phase near the La_0.67Sr_0.33MnO₃ and Nd_0.67Sr_0.33MnO₃ grain boundaries as indicated in the XRD pattern and SEM image. At 1100 °C, the formation of interfacial phases near the grain boundaries enhances the conductivity in the composite. Broad magnetoresistance across room temperature is observed in a composite sintered at 1300 °C. This observation may be ascribed to the coexistence of multiphase in the composite which leads to a decrease in resistance. The results suggest that sintering temperature has a prominent effect on the properties of the grain boundary, which plays an important role in determining the electrical transport behaviour of the composites.

The Fe₆₁Co₇Zr_9.5Mo₅W₂B_15.5 bulk metallic glass (BMG) has the best glass forming-ability (GFA), high thermal stability, and the highest strength (the compressive strength σ = 3800 MPa) among known Fe-based alloys. Unfortunately, this BMG does not have the same good soft magnetic properties as other Fe-based BMGs do. We report here that a small amount of Ni addition (microalloying) can significantly enhance the soft magnetic properties of the alloy without deteriorating its high GFA. The saturation magnetization is increased threefold, while the coercivity is decreased about 40-fold, with only 3 at.% Ni addition. The improvement is interpreted to result from the enhancement of the magnetic exchange interaction as the Ni content increases. The results indicate that it is possible to adjust the magnetic properties of Fe-based BMGs by a minor change in the content of some component. BMGs with good soft magnetic property, ultrahigh mechanical strength, good GFA and high thermal stability show some promise for future applications.

The magnetic ordering process of the antiferromagnet FeBr₂ has been studied by measuring low-field dc-magnetization, ac-susceptibility and the Mössbauer spectrum. All quantities measured show anomalous behaviour around the Néel temperature T_N = 14.2 K. We propose defining T_p (>T_N) by the temperature where the magnetization is maximum. Because it is T_p, not T_N, that signifies the onset of magnetic ordering. We indicate that FeBr₂ transforms from the paramagnetic to antiferromagnetic (AF) state through an intermediate AF domain state which exists in a certain narrow temperature region ΔT just below T_p. From the fact that ΔT is sample-dependent, we have inferred that the stacking fault of the hexagonal c-layers plays an important role in the formation of the intermediate AF domain state.

Recent experiments have shown that ordered half-metallic Sr₂FeMoO₆ exhibits a net moment of less than 4 μ_B. In disordered Sr₂FeMoO₆, the linear correlation between saturated magnetization and antisite defect concentration disagrees with the prediction of published models. In this paper, we propose a model which considers both contributions of ferromagnetic interaction (double-exchange mechanism) induced by itinerant spin-polarized carriers and antiferromagnetic interaction. Both in ordered and in disordered Sr₂FeMoO₆, the saturated magnetization is studied. It is found that the itinerant polarized carriers have a large effect on the saturated magnetization. Our calculation results explain experimental results very well.

Directional ordering in the amorphous Co₇₅Si₁₅B₁₀ alloys by means of the magnetic after-effect (MAE) of the initial reluctivity and its influence on the Perminvar effect have been investigated. Two peak MAE spectra were obtained from isochronal measurements for as-cast as well as annealed samples. The spectrum of the as-cast sample has peak maxima at 383 and 545 K. Comparing this MAE spectrum with the spectrum of amorphous Co₇₅B₂₅ alloy, we identified the first peak as a result of Co–B atom pair reorientation (B-type relaxation) and the second one at higher temperatures as a result of Co–Si atom pair reorientation (Si-type relaxation). After annealing, the peaks shift to 442 and 576 K, respectively. For the numerical analysis of Co₇₅Si₁₅B₁₀ MAE spectra we modified the micromagnetic model assuming the existence of more relaxation processes, where each process is connected to the relaxation of one metalloid element. The pre-exponential factor for B-type relaxation was found to be τ_0,AC^(B) = 7 × 10⁻¹⁷ s with the most probable activation energy Q_AC^*(B) = 1.31 eV. These values correlate very well with the magnetic relaxation (MR) activation parameters of Co₇₅B₂₅ alloy, τ_0,AC = 2 × 10⁻¹⁷ s and Q_AC^* = 1.35 eV. Si-type relaxation has activation parameters τ_0,AC^(Si) = 6 × 10⁻¹⁸ s and Q_AC^*(Si) = 1.96 eV. After annealing the sample at 683 K for 30 min they change to values τ_0,AN^(B) = 2 × 10⁻¹⁵ s, Q_AN^*(B) = 1.38 eV and τ_0,AN^(Si) = 3 × 10⁻¹⁷ s, Q_AN^*(Si) = 2.01 eV. The complicated shapes of the long-time isotherms reflect the superposition of two relaxation processes. We have numerically split each isotherm into two sub-isotherms representing the particular contributions of the two relaxation processes. The MAE spectrum of the critical field measured on the as-cast sample also has two peaks, like the reluctivity spectrum. The impact of Co–B and Co–Si atom pairs on the behaviour of the domain wall stabilization potential is discussed for the explanation of the observed MR results.

Bicrystal magnetoresistance hysteresis is studied within the model of coherent rotation of magnetization. The magnetoresistance hysteresis is calculated numerically in the limit of fully spin polarized current for symmetric bicrystal junctions with biaxial magnetic anisotropy and of varying misorientation angles. The shape of the curves obtained from the model displays different characteristic features, depending on the angular relationships, which are consistent with experimental data from the literature. The results show a magnetoresistance increasing with increasing misorientation angle. The influence of biaxial magnetocrystalline anisotropy is reflected in a hump in the maximum magnetoresistance curve at around a misorientation angle of 25°. This structure is absent in the case of uniaxial anisotropy.

The domain states and phase transitions in 0.62Pb(Mg_1/3Nb_2/3)O₃–0.38PbTiO₃ single crystals with different orientations were investigated through biased dielectric measurement, thermally stimulated discharging current (TSDC) and polarization–electric field (P–E) hysteresis loop measurements. The biased dielectric response shows that the crystals have a macrodomain tetragonal ferroelectric state in the ferroelectric phase under zero dc bias. An external bias field could modulate the domain state and induce a phase transition in the crystals. Also, it is proposed that a bias field applied along the direction of the original tetragonal phase could induce triple like P–E hysteresis loops and an orthorhombic ferroelectric phase in an intermediate temperature range.

Spectroscopic properties of Ho³⁺ in 67B₂O₃·xLi₂O ·(32− x)Na₂O, 67B₂O₃·xLi₂O ·(32− x)K₂O and 67B₂O₃·xLi₂O ·(32− x)Cs₂O (where x = 8, 12, 16, 20 and 24) glasses were investigated on the basis of Judd–Ofelt theory. Various spectroscopic parameters (E¹,E²,E³, ξ_4f, α and β) and Judd–Ofelt intensity parameters (Ω₂, Ω₄ and Ω₆) are calculated as a function of x in the three glass matrices. The obtained Judd–Ofelt intensity parameter Ω₂ increases with the addition of a second alkali and also shows minima or maxima at x = 16–20 mol % in the above glasses. Using Judd–Ofelt intensity parameters (Ω₂, Ω₄ and Ω₆), radiative transition probabilities (A_T), radiative lifetimes (τ_R), branching ratios (β) and integrated absorption cross sections (Σ) have been calculated for certain excited states of Ho³⁺. The non-radiative transition rates of different excited states of Ho³⁺ are also estimated from 'energy gap law'. From the luminescence spectra, stimulated emission cross-sections (σ_p) have been obtained for the two transitions and of Ho³⁺. The trend of all these parameters observed as a function of x in these glass systems have been discussed, keeping in mind the effect of mixed alkalis.

The electronic structures of hole-doped La_0.7Ca_0.3MnO₃ and electron-doped La_0.7Ce_0.3MnO₃ manganites are investigated by x-ray absorption near-edge structure spectroscopy at the O and Mn K-, and Mn L_3,2-edges. The Mn K- and L_3,2-edge results show that Ce dopants increase the occupation of the Mn 4p and majority-spin e_g orbitals and reduce the positive effective charge of some Mn ions. However, Ce doping also induces holes in O 2p derived states. As for La_0.7Ca_0.3MnO₃, in contrast to previous understanding that Ca doping converts some Mn ions into the Mn⁴⁺ state, we find that Ca dopants actually increase the number of majority-spin e_g electrons. We find instead that the holes created by Ca dopants are in the O 2p derived states.

A high pressure form of ZnO with a rock-salt structure can be synthesized as a thin film by a pulsed laser deposition technique when  mol% of MgO is alloyed. The phase is identified both by x-ray diffraction and near edge x-ray absorption fine structure (NEXAFS) measurements. NEXAFS is interpreted with the aid of first principles calculations employing a supercell composed of 108 atoms with a Zn-1s core-hole. The rock-salt phase can be formed only when an MgO(100) substrate is used because of a favourable lattice matching. As a result of the heteroepitaxy, the crystal is distorted tetragonally by c/a = 1.02. The energy increase due to the tetragonal deformation is estimated to be 2 meV/ZnO by a first principles calculation.