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Thin films of the ferromagnetic metal SrRuO3 (SRO) show a varying easy magnetization axis depending on the epitaxial strain and undergo a metal-to-insulator transition with decreasing film thickness. We have investigated the magnetic properties of SRO thin films with varying thicknesses fabricated on SrTiO3(001) substrates by soft x-ray magnetic circular dichroism (XMCD) at the Ru M2,3 edge. Results have shown that, with decreasing film thickness, the film changes from ferromagnetic to non-magnetic around 3monolayer thickness, consistent with previous magnetization and magneto-optical Kerr effect measurements. The orbital magnetic moment perpendicular to the film was found to be ~ 0.1{\mu}B/Ru atom, and remained nearly unchanged with decreasing film thickness while the spin magnetic moment decreases. Mechanism for the formation of the orbital magnetic moment is discussed based on the electronic structure of the compressively strained SRO film., Comment: 6 pages, 6 figures, Submitted in Phys. Rev. B

We report on theoretical and experimental investigation of A-site driven ferroelectricity in ferromagnetic La2NiMnO6 thin films grown on SrTiO3 substrates. Structural analysis and density functional theory calculations show that epitaxial strain stretches the rhombohedral La2NiMnO6 crystal lattice along the [111]cubic direction, triggering a displacement of the A-site La ions in the double perovskite lattice. The lattice distortion and the A-site displacements stabilize a ferroelectric polar state in ferromagnetic La2NiMnO6 crystals. The ferroelectric state only appears in the rhombohedral La2NiMnO6 phase, where MnO6 and NiO6 octahedral tilting is inhibited by the 3-fold crystal symmetry. Electron localization mapping showed that covalent bonding with oxygen and 6s orbital lone pair formation are negligible in this material., Comment: in press

Background:The design of new nuclear reactors and transmutation devices requires to reduce the present neutron cross section uncertainties of minor actinides. Purpose: Reduce the $^{243}$Am(n,$\gamma$) cross section uncertainty. Method: The $^{243}$Am(n,$\gamma$) cross section has been measured at the n_TOF facility at CERN with a BaF$_{2}$ Total Absorption Calorimeter, in the energy range between 0.7 eV and 2.5 keV. Results: The $^{243}$Am(n,$\gamma$) cross section has been successfully measured in the mentioned energy range. The resolved resonance region has been extended from 250 eV up to 400 eV. In the unresolved resonance region our results are compatible with one of the two incompatible capture data sets available below 2.5 keV. The data available in EXFOR and in the literature has been used to perform a simple analysis above 2.5 keV. Conclusions: The results of this measurement contribute to reduce the $^{243}$Am(n,$\gamma$) cross section uncertainty and suggest that this cross section is underestimated up to 25% in the neutron energy range between 50 eV and a few keV in the present evaluated data libraries.

The electronic and magnetic properties of Fe atoms in the ferromagnetic semiconductor (In,Fe)As codoped with Be have been studied by x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe $L_{2,3}$ edge. The XAS and XMCD spectra showed simple spectral line shapes similar to Fe metal, but the ratio of the orbital and spin magnetic moments ($M_\mathrm{orb}$/$M_\mathrm{spin}$) estimated using the XMCD sum rules was significantly larger than that of Fe metal, indicating a significant orbital moment of Fe $3d$ electrons in (In,Fe)As:Be. The positive value of $M_\mathrm{orb}$/$M_\mathrm{spin}$ implies that the Fe $3d$ shell is more than half-filled, which arises from the hybridization of the Fe$^{3+}$ ($d^5$) state with the charge-transfer $d^6\underline{L}$ states, where $\underline{L}$ is a ligand hole in the host valence band. The XMCD intensity as a function of magnetic field indicated hysteretic behavior of the superparamagnetic-like component due to discrete ferromagnetic domains., Comment: 4 pages, 2 figures, 1 table

We report measurements of the gate-bias dependent band alignment, especially the confining potential profile, at the conducting LaAlO3/SrTiO3 (001) heterointerface using soft and hard x-ray photoemission spectroscopy. Depth-profiling analysis reveals that a significant potential drop on the SrTiO3 side of the interface occurs within ~2 nm of the interface under negative gate bias voltage. These results demonstrate gate control of the collapse of permittivity at the interface, and explain the dramatic loss of electron mobility with back-gate depletion., Comment: 16 pages, 4 figures

We have investigated the electronic and magnetic properties of Co-doped Pr0.8Ca0.2MnO3 thin films using various spectroscopic techniques. X-ray absorption and hard x-ray photoemission spectroscopy revealed that the substituted Co ions are in the divalent state, resulting in hole doping on the Mn atoms. Studies of element-selective magnetic properties by x-ray magnetic circular dichroism found a large orbital magnetic moment for the Co ions. These spectroscopic studies reveal that the substituted Co ions play several roles of hole doping for Mn, ferromagnetic superexchange coupling between the Co2+ and Mn4+ ions, and orbital magnetism of the Co2+ ions. Competition among these complex interactions produces the unique electronic and magnetic behaviors including enhanced coercivity of the Co-doped Pr0.8Ca0.2MnO3., Comment: 7 pages and 6 figures

We investigate the electronic structure of a perovskite-type Pauli paramagnet SrMoO3 (t2g2) thin film using hard x-ray photoemission spectroscopy and compare the results to the realistic calculations that combine the density functional theory within the local-density approximation (LDA) with the dynamical-mean field theory (DMFT). Despite the clear signature of electron correlations in the electronic specific heat, the narrowing of the quasiparticle bands is not observed in the photoemission spectrum. This is explained in terms of the characteristic effect of Hund's rule coupling for partially-filled t2g bands, which induces strong quasiparticle renormalization already for values of Hubbard interaction which are smaller than the bandwidth. The interpretation is supported by additional model DMFT calculations including Hund's rule coupling, that show renormalization of low-energy quasiparticles without affecting the overall bandwidth. The photoemission spectra show additional spectral weight around -2 eV that is not present in the LDA+DMFT. We interpret this weight as a plasmon satellite, which is supported by measured Mo, Sr and Oxygen core-hole spectra that all show satellites at this energy., Comment: 8 pages, 7 figures

The electronic structure of doped Mn in (Ga,Mn)As is studied by resonant inelastic X-ray scattering (RIXS). From configuration-interaction cluster-model calculations, the line shapes of the Mn $L_3$ RIXS spectra can be explained by $d$-$d$ excitations from the Mn$^{3+}$ ground state, dominated by charge-transferred states, rather than a Mn$^{2+}$ ground state. Unlike archetypical $d$-$d$ excitation, the peak widths are broader than the experimental energy resolution. We attribute the broadening to a finite lifetime of the $d$-$d$ excitations, which decay rapidly to electron-hole pairs in the host valence and conduction bands through hybridization of the Mn $3d$ orbital with the ligand band., Comment: 5 pages, 3 figures

We report the detailed electronic structure of a hole-doped delafossite oxide CuCr_{1-x}Mg_{x}O_{2} (0 <= x <= 0.03) studied by photoemission spectroscopy (PES), soft x-ray absorption spectroscopy (XAS), and band-structure calculations within the local-density approximation +U (LDA+U) scheme. Cr/Cu 3p-3d resonant PES reveals that the near-Fermi-level leading structure has primarily the Cr 3d character with a minor contribution from the Cu 3d through Cu 3d-O 2p-Cr 3d hybridization, having good agreement with the band-structure calculations. This indicates that a doped hole will have primarily the Cr 3d character. Cr 2p PES and L-edge XAS spectra exhibit typical Cr^{3+} features for all x, while the Cu L-edge XAS spectra exhibited a systematic change with x. This indicates now that the Cu valence is monovalent at x=0 and the doped hole should have Cu 3d character. Nevertheless, we surprisingly observed two types of charge-transfer satellites that should be attributed to Cu^{+} (3d^{10}) and Cu^{2+} (3d^{9}) like initial states in Cu 2p-3d resonant PES spectrum for at x=0, while Cu 2p PES spectra with no doubt shows the Cu^{+} character even for the lightly doped samples. We propose that these contradictory results can be understood by introducing no only the Cu 4s state, but also finite Cu 3d,4s-Cr 3d charge transfer via O 2p states in the ground-state electronic configuration., Comment: 9 pages, 9 figures, revised version accepted for publication in Phys. Rev. B

High spin states of 80Rb are studied via the fusion-evaporation reactions 65Cu+19F, 66Zn+18O and 68Zn+16O with the beam energies of 75 MeV, 76 MeV and 80 MeV, respectively. Twenty-three new states with twenty-eight new \gamma transitions were added to the previously proposed level scheme, where the second negative-parity band is significantly pushed up to spins of 22^{-} and 15^{-} and two new sidebands are built on the known first negative-parity band. Two successive band crossings with frequencies 0.51 MeV and 0.61 MeV in the \alpha=0 branch as well as another one in the \alpha=1 branch of the second negative-parity band are observed for the first time. Signature inversions occur in the positive- and first negative-parity bands at the spins of 11\hbar and 15\hbar, respectively. The signature splitting is seen obviously in the second negative-parity band, but the signature inversion is not observed. It is also found that the structure of the two negative-parity bands is similar to that of its isotone ^{82}Y. Signature inversion in the positive-parity yrast band with configuration \pi g_{9/2} \otimes \nu g_{9/2} in this nucleus is discussed using the projected shell model (PSM).

Efficient injection of spin-polarized current into a semiconductor is a basic prerequisite for building semiconductor-based spintronic devices. Here, we use inelastic electron tunneling spectroscopy to show that the efficiency of spin-filter-type spin injectors is limited by spin scattering of the tunneling electrons. By matching the Fermi-surface shapes of the current injection source and target electrode material, spin injection efficiency can be significantly increased in epitaxial ferromagnetic insulator tunnel junctions. Our results demonstrate that not only structural but also Fermi-surface matching is important to suppress scattering processes in spintronic devices., Comment: 5 pages, 4 figures

The correlated electronic structure of SrVO3 has been investigated by angle-resolved photoemission spectroscopy using in-situ prepared thin films. Pronounced features of band renormalization have been observed: a sharp kink ~60 meV below the Fermi level (EF) and a broad so-called "high-energy kink" ~0.3 eV below EF as in the high-Tc cuprates although SrVO3 does not show magnetic fluctuations. We have deduced the self-energy in a wide energy range by applying the Kramers-Kronig relation to the observed spectra. The obtained self-energy clearly shows a large energy scale of ~0.7 eV which is attributed to electron-electron interaction and gives rise to the ~0.3 eV "kink" in the band dispersion as well as the incoherent peak ~1.5eV below EF. The present analysis enables us to obtain consistent picture both for the incoherent spectra and the band renormalization., Comment: 5 pages, 3 figures

Ferromagnetic insulator Pr0.8Ca0.2Mn1-yCoyO3 (0 <= y <= 0.7) thin films were epitaxially grown on (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 (100) substrates by pulsed laser deposition. To probe the ferromagnetic insulator state of hole-doped manganites, the Co content dependences of the structural, magnetic, and transport properties were studied. Variation of lattice constant by the substitution of Co ions is well reproduced considering that divalent and trivalent Co ions substitute for Mn ions at the perovskite B-sites. For 0 <= y <= 0.3, the Curie temperature, saturation magnetization, and magnetoresistance increase with increasing Co content, retaining the insulating properties. Detailed analyses of transport and magnetic properties indicate the contribution of both double exchange and superexchange interactions to the appearance of the ferromagnetic insulating phase., Comment: 3 pages, 3 figures

A rotational band with five $\gamma$-ray transitions ranging from 2$^{+}$ to 12$^{+}$ states was identified in $^{40}$Ar. This band is linked through $\gamma$ transitions from the excited 2$^{+}$, 4$^{+}$ and 6$^{+}$ levels to the low-lying states; this determines the excitation energy and the spin-parity of the band. The deduced transition quadrupole moment of 1.45$^{+0.49}_{-0.31} eb$ indicates that the band has a superdeformed shape. The nature of the band is revealed by cranked Hartree--Fock--Bogoliubov calculations and a multiparticle--multihole configuration is assigned to the band.

The authors report on the crystallographic orientation dependence of the Schottky properties for heterojunctions between a half-metallic ferromagnet La$_0.6$Sr$_0.4$MnO$_3$ (LSMO) and Nb-doped SrTiO3 semiconductor. The Schottky barrier height determined by in situ photoemission measurements is independent for the substrate orientations (001) and (110), while the magnetic properties of LSMO (110) films are more enhanced than for (001) films. These results suggest that the performance of magnetic devices based on ferromagnetic manganite is improved by using (110)-oriented substrates., Comment: 18 pages, 4 figures

We have investigated the shifts of the core-level photoemission spectra of La$_{0.6}$Sr$_{0.4}$MnO$_3$ thin films grown on three kinds of substrates, SrTiO$_3$, (LaAlO$_3$)$_{0.3}$-(SrAl$_{0.5}$Ta$_{0.5}$O$_3$)$_{0.7}$, and LaAlO$_3$. The experimental shifts of the La 4d and Sr 3d core levels are almost the same as the calculation, which we attribute to the absence of covalency effects on the Madelung potentials at these atomic sites due to the nearly ionic character of these atoms. On the other hand, the experimental shifts of the O $1s$ and Mn $2p$ core levels are negligibly small, in disagreement with the calculation. We consider that this is due to the strong covalent character of the Mn-O bonds., Comment: 4 pages, 5 figures

We have performed systematic tight-binding (TB) analyses of the angle-resolved photoemission spectroscopy (ARPES) spectra of transition-metal (TM) oxides A$M$O$_3$ ($M=$ Ti, V, Mn, and Fe) with the perovskite-type structure and compared the obtained parameters with those obtained from configuration-interaction (CI) cluster-model analyses of photoemission spectra. The values of $\epsilon_d-\epsilon_p$ from ARPES are found to be similar to the charge-transfer energy $\Delta$ from O $2p$ orbitals to empty TM 3d orbitals and much larger than $\Delta-U/2$ ($U$: on-site Coulomb energy) expected for Mott-Hubbard-type compounds including SrVO$_3$. $\epsilon_d-\epsilon_p$ values from {\it ab initio} band-structure calculations show similar behaviors to those from ARPES. The values of the $p-d$ transfer integrals to describe the global electronic structure are found to be similar in all the estimates, whereas additional narrowing beyond the TB description occurs in the ARPES spectra of the $d$ band., Comment: 5 pages, 3 figures

We have performed a detailed angel-resolved photoemission spectroscopy study of in-situ prepared SrVO3 thin films. Naturally capped by a ``transparent'' protective layer, contributions from surface states centered at ~ -1.5 eV are dramatically reduced, enabling us to study the bulk V 3d states. We have observed a clear band dispersion not only in the coherent quasiparticle part but also in the incoherent part, which are reproduced by dynamical mean-field theory calculations and the spectral weight of the incoherent part is stronger within the Fermi surface.

We have studied the electronic structure at the heterointerface between the band insulators LaAlO$_3$ and SrTiO$_3$ using $in situ$ photoemission spectroscopy. Our experimental results clearly reveal the formation of a notched structure on the SrTiO$_3$ side due to band bending at the metallic LaAlO$_3$/TiO$_2$-SrTiO$_3$ interface. The structure, however, is absent at the insulating LaAlO$_3$/SrO-SrTiO$_3$ interface. The present results indicate that the metallic states originate not from the charge transfer through the interface on a short-range scale but from the accumulation of carriers on a long-range scale., Comment: 20 pages, 4 figures

The magnetic properties of as-grown Ga$_{1-x}$Mn$_{x}$As have been investigated by the systematic measurements of temperature and magnetic field dependent soft x-ray magnetic circular dichroism (XMCD). The {\it intrinsic} XMCD intensity at high temperatures obeys the Curie-Weiss law, but residual spin magnetic moment appears already around 100 K, significantly above Curie temperature ($T_C$), suggesting that short-range ferromagnetic correlations are developed above $T_C$. The present results also suggest that antiferromagnetic interaction between the substitutional and interstitial Mn (Mn$_{int}$) ions exists and that the amount of the Mn$_{int}$ affects $T_C$., Comment: 4 pages, 4 figures

We have studied the O 2p valence-band structure of Nb-doped SrTiO3, in which a dilute concentration of electrons are doped into the d0 band insulator, by angle-resolved photoemission spectroscopy (ARPES) measurements. We found that ARPES spectra at the valence band maxima at the M [k = (pi/a, pi/a, 0)]and R [k = (pi/a, pi/a, pi/a)] points start from ~ 3.3 eV below the Fermi level (EF), consistent with the indirect band gap of 3.3 eV and the EF position at the bottom of the conduction band. The peak position of the ARPES spectra were, however, shifted toward higher binding energies by ~ 500 meV from the 3.3 eV threshold. Because the bands at M and R have pure O 2p character, we attribute this ~ 500 meV shift to strong coupling of the oxygen p hole with optical phonons in analogy with the peak shifts observed for d-electron photoemission spectra in various transition-metal oxides.

We have performed a depth profile study of thermally diffused Mn/GaAs (001) interfaces using photoemission spectroscopy combined with Ar$^+$-ion sputtering. We found that Mn ion was thermally diffused into the deep region of the GaAs substrate and completely reacted with GaAs. In the deep region, the Mn 2$p$ core-level and Mn 3$d$ valence-band spectra of the Mn/GaAs (001) sample heated to 600 $^{\circ}$C were similar to those of Ga$_{1-x}$Mn$_x$As, zinc-blende-type MnAs dots, and/or interstitial Mn in tetrahedrally coordinated by As atoms, suggesting that the Mn 3$d$ states were essentially localized but were hybridized with the electronic states of the host GaAs. Ferromagnetism was observed in the dilute Mn phase., Comment: 5 pages, 4 figures

We have performed an {\it in-situ} photoemission study of Pr_{1-x}Ca_xMnO_3 (PCMO) thin films grown on LaAlO_3 (001) substrates and observed the effect of epitaxial strain on the electronic structure. We found that the chemical potential shifted monotonically with doping, unlike bulk PCMO, implying the disappearance of incommensurate charge fluctuations of bulk PCMO. In the valence-band spectra, we found a doping-induced energy shift toward the Fermi level (E_F) but there was no spectral weight transfer, which was observed in bulk PCMO. The gap at E_F was clearly seen in the experimental band dispersions determined by angle-resolved photoemission spectroscopy and could not be explained by the metallic band structure of the C-type antiferromagnetic state, probably due to localization of electrons along the ferromagnetic chain direction or due to another type of spin-orbital ordering., Comment: 5 pages, 4 figures

We report the first observation of changes in the electronic structure of La$_{1-x}$Sr$_{x}$MnO$_{3}$ (LSMO) across the filling-control metal-insulator (MI) transition by means of in situ angle-resolved photoemission spectroscopy (ARPES) of epitaxial thin films. The Fermi surface gradually disappears near the MI transition by transferring the spectral weight from the coherent band near the Fermi level ($E_{F}$) to the lower Hubbard band, whereas a pseudogap behavior also exists in the ARPES spectra in the close vicinity of $E_{F}$ for the metallic LSMO. These results indicate that the spectral weight transfer derived from strong electron-electron interaction dominates the gap formation in LSMO associated with the filling-control MI transition., Comment: 11 pages, 4 figures

We have measured photoemission spectra of two kinds of TiO$_2$-capped VO$_2$ thin films, namely, that with rutile-type TiO$_2$ (r-TiO$_2$/VO$_2$) and that with amorphous TiO$_2$ (a-TiO$_2$/VO$_2$) capping layers. Below the Metal-insulator transition temperature of the VO$_2$ thin films, $\sim 300$ K, metallic states were not observed for the interfaces with TiO$_2$, in contrast with the interfaces between the band insulator SrTiO$_3$ and the Mott insulator LaTiO$_3$ in spite of the fact that both TiO$_2$ and SrTiO$_3$ are band insulators with $d^0$ electronic configurations and both VO$_2$ and LaTiO$_3$ are Mott insulators with $d^1$ electronic configurations. We discuss possible origins of this difference and suggest the importance of the polarity discontinuity of the interfaces. Stronger incoherent part was observed in r-TiO$_2$/VO$_2$ than in a-TiO$_2$/VO$_2$, suggesting Ti-V atomic diffusion due to the higher deposition temperature for r-TiO$_2$/VO$_2$., Comment: 5 pages, 6 figures

We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level ($E_F$) as a function of carrier concentration in Pr$_{1-x}$Ca$_x$MnO$_3$ (PCMO, $0.2 \le x \le 0.65$) through the measurements of photoemission spectra. The results showed that the chemical potential shift was suppressed for $x \agt 0.3$, where the charge exchange (CE)-type antiferromagnetic charge-ordered state appears at low temperatures. We consider this observation to be related to charge self-organization such as stripe formation on a microscopic scale in this composition range. Together with the previous observation of monotonous chemical potential shift in La$_{1-x}$Sr$_x$MnO$_3$, we conclude that the tendency toward the charge self-organization increases with decreasing bandwidth. In the valence band, spectral weight of the Mn 3$d$ $e_g$ electrons in PCMO was transferred from $\sim$ 1 eV below $E_F$ to the region near $E_F$ with hole doping, leading to a finite intensity at $E_F$ even in the paramagnetic insulating phase for $x \agt 0.3$, probably related with the tendency toward charge self-organization. The finite intensity at $E_F$ in spite of the insulating transport behavior is consistent with fluctuations involving ferromagnetic metallic states., Comment: 6 pages, 5 figures

We have measured photoemission spectra of SrTiO3/LaTiO3 superlattices with a topmost SrTiO3 layer of variable thickness. Finite coherent spectral weight with a clear Fermi cut-off was observed at chemically abrupt SrTiO3/LaTiO3 interfaces, indicating that an ``electronic reconstruction'' occurs at the interface between the Mott insulator LaTiO3 and the band insulator SrTiO3. For SrTiO3/LaTiO3 interfaces annealed at high temperatures (~ 1000 C), which leads to Sr/La atomic interdiffusion and hence to the formation of La1-xSrxTiO3-like material, the intensity of the incoherent part was found to be dramatically reduced whereas the coherent part with a sharp Fermi cut-off is enhanced due to the spread of charge. These important experimental features are well reproduced by layer dynamical-mean-field-theory calculation.

Nowadays it has become feasible to perform angle-resolved photoemission spectroscopy (ARPES) measurements of transition-metal oxides with three-dimensional perovskite structures owing to the availability of high-quality single crystals of bulk and epitaxial thin films. In this article, we review recent experimental results and interpretation of ARPES data using empirical tight-binding band-structure calculations. Results are presented for SrVO$_3$ (SVO) bulk single crystals, and La$_{1-x}$Sr$_x$FeO$_3$ (LSFO) and La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films. In the case of SVO, from comparison of the experimental results with calculated surface electronic structure, we concluded that the obtained band dispersions reflect the bulk electronic structure. The experimental band structures of LSFO and LSMO were analyzed assuming the G-type antiferromagnetic state and the ferromagnetic state, respectively. We also demonstrated that the intrinsic uncertainty of the electron momentum perpendicular to the crystal surface is important for the interpretation of the ARPES results of three-dimensional materials., Comment: 25 pages, 12 figures

We have performed an angle-resolved photoemission spectroscopy study of La$_{0.6}$Sr$_{0.4}$FeO$_3$ using {\it in situ} prepared thin films and determined its band structure. The experimental band dispersions could be well explained by an empirical band structure assuming the G-type antiferromagnetic state. However, the Fe 3d bands were found to be shifted downward relative to the Fermi level ($E_F$) by $\sim 1$ eV compared with the calculation and to form a (pseudo)gap of $\sim 1$ eV at $E_F$. We attribute this observation to a strong localization effect of doped holes due to polaron formation., Comment: 5 pages, 5 figures

We have investigated the interfacial electronic structure of La0.6Sr0.4MnO3 (LSMO)/ SrTiO3 (STO)/ LSMO heterojunctions utilizing the elemental selectivity of photoemission spectroscopy. The Ti 2p core-level spectra clearly show Ti4+ states and do not exhibit any indication of Ti3+ states in TiO2 layers irrespective of a different kind of adjacent atomic layer with different chemical carrier concentration. This result indicates that the Ti ions in the TiO2 atomic layers preserve their tetravalent states even in the vicinity of the valence-mismatched interface between LSMO and STO, reflecting chemical stability of the Ti4+ states., Comment: 12 pages, 3 figures

Perovskite-type BiNiO$_3$ is an insulating antiferromagnet in which a charge disproportionation occurs at the Bi site. La substitution for Bi suppresses the charge disproportionation and makes the system metallic. We have measured the photoemission and x-ray absorption (XAS) spectra of Bi$_{1-x}$La$_{x}$NiO$_{3}$ to investigate how the electronic structure changes with La doping. From Ni $2p$ XAS, we observed an increase of the valence of Ni from 2+ toward 3+. Combined with the core-level photoemission study, it was found that the average valence of Bi remains $\sim 4+$ and that the Ni valence behaves as $\sim (2+x)+$, that is, La substitution results in hole doping at the Ni sites. In the valence-band photoemission spectra, we observed a Fermi cutoff for $x>0$, consistent with the metallic behavior of the La-doped compounds. The Ni $2p$ XAS, Ni $2p$ core-level photoemission, and valence-band photoemission spectra were analyzed by configuration-interaction cluster-model calculation, and the spectral line shapes were found to be consistent with the gradual Ni$^{2+} \to$ Ni$^{3+}$ valence change., Comment: 6 pages, 7 figures

We have performed an in situ angle-resolved photoemission spectroscopy (ARPES) on single-crystal surfaces of La$_{0.6}$Sr$_{0.4}$MnO$_{3}$ (LSMO) thin films grown on SrTiO$_{3}$ (001) substrates by laser molecular beam epitaxy, and investigated the electronic structure near the Fermi level ($E_{F}$). The experimental results were compared with the band-structure calculation based on LDA + $U$. The band structure of LSMO thin films consists of several highly dispersive O 2$p$ derived bands in the binding energy range of 2.0 - 6.0 eV and Mn 3$d$ derived bands near $E_{F}$. ARPES spectra around the $Gamma$ point show a dispersive band near $E_{F}$ indicative of an electron pocket centered at the $Gamma$ point, although it was not so clearly resolved as an electronlike pocket due to the suppression of spectral weight in the vicinity of $E_{F}$. Compared with the band-structure calculation, the observed conduction band is assigned to the Mn 3$de_{g}$ majority-spin band responsible for the half-metallic nature of LSMO. We have found that the estimated size of the Fermi surface is consistent with the prediction of the band-structure calculation, while the band width becomes significantly narrower than the calculation. Also, the intensity near $E_{F}$ is strongly reduced. The origin of these discrepancies between the experiment and the calculation is discussed., Comment: 7 pages, 5 figures

We have measured soft x-ray photoemission and O 1{\it s} x-ray absorption spectra of Ca$_{1-x}$Sr$_x$RuO$_3$ thin films prepared {\it in situ}. The coherent and incoherent parts have been identified in the bulk component of the photoemission spectra, and spectral weight transfer from the coherent to the incoherent part has been observed with decreasing $x$, namely, with increasing orthorhombic distortion. We propose that, while the Ru 4d one-electron bandwidth does not change with $x$, the distortion and hence the splitting of the $t_{2\text{g}}$ band effectively increases electron correlation strength. Although strong mass enhancement is found in the electronic specific heat data, the coherent part remains wide, suggesting enhanced band narrowing only in the vicinity of {\it E$_{F}$}.

We have measured the temperature dependence of the photoemission and x-ray absorption spectra of La$_{1-x}$Sr$_x$FeO$_3$ (LSFO) epitaxial thin films with $x=0.67$, where charge disproportionation ($3{Fe}^{3.67+}\to 2{Fe}^{3+}+ {Fe}^{5+}$) resulting in long-range spin and charge ordering is known to occur below $T_{CD}=190$ K. With decreasing temperature we observed gradual changes of the spectra with spectral weight transfer over a wide energy range of $\sim 5$ eV. Above $T_{CD}$ the intensity at the Fermi level ($E_F$) was relatively high compared to that below $T_{CD}$ but still much lower than that in conventional metals. We also found a similar temperature dependence for $x=0.4$, and to a lesser extent for $x=0.2$. These observations suggest that a local charge disproportionation occurs not only in the $x=0.67$ sample below $T_{CD}$ but also over a wider temperature and composition range in LSFO. This implies that the tendency toward charge disproportionation may be the origin of the unusually wide insulating region of the LSFO phase diagram., Comment: 6 pages, 8 figures

We have investigated change in the electronic structures of atomically-controlled La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films as a function of hole-doping level ($x$) in terms of {\it in situ} photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The {\it in situ} PES measurements on a well-ordered surface of high-quality epitaxial LSMO thin films enable us to reveal their intrinsic electronic structures, especially the structure near the Fermi level ($E_F$). We have found that overall features of valence band as well as the core levels monotonically shifted toward lower binding energy as $x$ was increased, indicating the rigid-band like behavior of underlying electronic structure of LSMO thin films. The peak nearest to $E_F$ due to the $e_g$ orbital is also found to move toward $E_F$ in a rigid-band manner, while the peak intensity decreases with increasing $x$. The loss of spectral weight with $x$ in the occupied density of states was compensated by simultaneous increment of the shoulder structure in O 1$s$ XAS spectra, suggesting the existence of a pseudogap, that is depression in spectral weight at $E_F$, for all metallic compositions. These results indicate that the simple rigid-band model does not describe the electronic structure near $E_F$ of LSMO and that the spectral weight transfer from below to above $E_F$ across the gap dominates the spectral changes with $x$ in LSMO thin films., Comment: 8 pages, 8 figures

Using hard x-ray (HX ; $h\nu$ = 5.95 keV) synchrotron photoemission spectroscopy (PES), we study the intrinsic electronic structure of La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films. Comparison of Mn 2$p$ core-levels with Soft x-ray (SX ; $h\nu$ $\sim$ 1000 eV) -PES shows a clear additional well-screened feature only in HX-PES. Take-off-angle dependent data indicate its bulk ($\ge$ 20 {\AA}) character. The doping and temperature dependence track the ferromagnetism and metallicity of the LSMO series. Cluster model calculations including charge transfer from doping induced states show good agreement, confirming this picture of bulk properties reflected in Mn 2$p$ core-levels using HX-PES., Comment: 4 pages, 4 figures; accepted for publication in Phys. Rev. Lett

We have studied the electronic structure of epitaxially grown thin films of La$_{1-x}$Sr$_x$FeO$_3$ by {\it in-situ} photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The Fe 2$p$ and valence-band PES spectra and the O $1s$ XAS spectra of LaFeO$_3$ have been successfully reproduced by configuration-interaction cluster-model calculation and, except for the satellite structure, by band-structure calculation.From the shift of the binding energies of core levels, the chemical potential was found to be shifted downward as $x$ was increased. Among the three peaks in the valence-band spectra of La$_{1-x}$Sr$_x$FeO$_3$, the peak nearest to the Fermi level ($E_F$), due to the ``$e_{g}$ band'', was found to move toward $E_F$ and became weaker as $x$ was increased, whereas the intensity of the peak just above $E_F$ in the O $1s$ XAS spectra increased with $x$. The gap or pseudogap at $E_F$ was seen for all values of $x$. These results indicate that changes in the spectral line shape around $E_F$ are dominated by spectral weight transfer from below to above $E_F$ across the gap and are therefore highly non-rigid-band-like., Comment: 8 pages, 7 figures

We present an angle-resolved photoemission (ARPES) study on the layered transition-metal dichalcogenide 1{\em T}-TaS$_{1.2}$Se$_{0.8}$ in the metallic commensurate charge-density-wave (CDW) phase. A model calculation of the spectral function captures the main features of the ARPES spectra well qualitatively, that is, the gross splits of unreconstructed band structure in the absence of the CDW superlattice. The observed enhancement of the size of the gap between the lower and middle fragments of the Ta {\em 5d} band along the $\Gamma$M line by cooling is interpreted in terms of the increase in the CDW-related potential., Comment: 5 pages, 4 figures

Lifetimes of the yrast states in 120Xe and ground state band below and above band crossing in 118Te have been measured by DSAM in the 111Cd(12C,3n) reaction and by DSAM and RDM in the 109Ag(13C,p3n) reaction, respectively. The results are compared with E2 transition probabilities in 119I and 128Ba. The experimental data are compared with calculation done in the framework of the IBM1 model in the O(6) and SU(5) limits., Comment: Contributed paper at "High Spin Physics 2001", see http://www.fuw.edu.pl/~hs2001/ , to be published in Acta Physica Polonica B