Common use of Experiment Clause in Contracts

Experiment. The photo-emission data were obtained at the Swedish synchrotron radiation facility MAX-lab using the surface end station of the I511 undulator × beamline49. The samples were prepared in a local molecular beam epitaxy system and were transferred to the photo-emission station in a portable ultrahigh vacuum chamber without being exposed to the atmosphere. The Mn concentrations were determined during growth by means of reflection high-energy electron diffraction oscillations, as described earlier50. Survey spectra recorded after transfer showed contamination-free surfaces, and low-energy electron diffraction showed (1 2) × × surface reconstruction. For very low Mn concentration (0.1%), the fractional spots of GaAs(100) c(4 4) were still present, but clearly stretched along the /100S azimuths, reflecting a transition for (1 2) pattern. All spectra presented here were obtained at room temperature from as-grown samples, that is, samples not subjected to postgrowth annealing. After the photo-emission experiment, the magnetic properties were measured ex situ in a SQUID setup. The sample with 6% Mn showed ferromagnetic behaviour below 55 K, whereas none of the other samples showed long-range order above 5 K.‌‌ scheme was applied to explicitly treat the local Coulomb interaction between the localized Mn-3d electrons. The 4-index rotationally invariant Coulomb interaction matrix was generated from the ▇▇▇▇▇▇ parameters F0, F2 and F4. The choice of the average Coulomb repulsion F0, which corresponds to the ▇▇▇▇▇▇▇ U, is rather problematic, as no calculations based on constrained LDA or random phase approximation (RPA) methods are found in the literature. Therefore, we have considered values between 4 and 7 eV, which are the accepted strengths of the Coulomb repulsion for bulk metallic g-Mn (ref. 48) and MnO (ref. 45). The main results of the paper are presented for the intermediate value U 6 eV, whereas results for smaller and larger values are discussed at the end of the Results section. F2 and F4 are easier to evaluate and therefore were calculated directly from the electronic density as done in the study by ▇▇▇▇▇▇▇▇¨m et al.45. The calculated values correspond to the average Hund’s exchange parameter JC1 eV. The LDA DMFT results for J 0.8 eV, shown in Fig. 4, were based on F 2 and F4 obtained by means = = + of fixed atomic ratios41,42. + = The effective impurity problem arising in LDA DMFT has been solved through exact diagonalization method, as described in the study by Thunstro¨m et al.45 The fermionic bath interacting with the atomic impurity has been approximated by means of 22 auxiliary bath spin-orbitals: 18 bath states were coupled to the strongly hybridizing Mn t2g states, whereas only 4 bath states were coupled to the weakly hybridizing Mn eg states. All the calculations have been made for the paramagnetic phase at T 400 K and using 1,200 fermionic Matsubara frequencies, and double-counting problem has been considered in the fully localized limit41,42. Finally, in the calculation of the hole densities, we have considered only the atoms included in one supercell and their multiplicity, consistently with our physical modelling and previous literature38. References