Low energy excitations in CoO studied by temperature dependent x-ray absorption spectroscopy (2008)
Haverkort, M. W., Tanaka, A., Hu, Z., Hsieh, H. H., Chen, C. T., ...
We have measured the intricate temperature dependence of the Co L2,3 x-ray absorption spectra (2p-3d excitations) of CoO. To allow for accurate total electron yield measurements, the material has...
Image charge screening: a new approach to enhance magnetic ordering temperatures (2008)
Altieri, S., Finazzi, M., Hsieh, H. H., Haverkort, M. W., Chen, C. T., ...
We have tested the concept of image charge screening as a new approach to enhance magnetic ordering temperatures and superexchange interactions in ultra thin films. Using a 3 monolayer NiO(100) film...
Hansmann, P., Severing, A., Hu, Z., Haverkort, M. W., Chang, C. F., Klein, S., ...
We infer that soft-x-ray absorption spectroscopy is a versatile method for the determination of the crystal-field ground state symmetry of rare earth Heavy Fermion systems, complementing neutron...
Burnus, T., Hu, Z., Hsieh, H. H., Joly, V. L. J., Joy, P. A., Haverkort, M. W., ...
We have studied the local electronic structure of LaMn0.5Co0.5O3 using soft-x-ray absorption spectroscopy at the Co-L_3,2 and Mn-L_3,2 edges. We found a high-spin Co^{2+}--Mn^{4+} valence state for...
The spin state transition in LaCoO$_{3}$; revising a revision (2006)
Haverkort, M. W., Hu, Z., Cezar, J. C., Burnus, T., Hartmann, H., Reuther, M., ...
Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-$L_{2,3}$ edge we reveal that the spin state transition in LaCoO$_{3}$ can be well described by a low-spin ground...
Coherence-enhanced synchrotron radiology: Refraction versus diffraction mechanisms (2006)
Hwu, Y., Hsieh, H. H., Lu, M. J., Tsai, W. L., Lin, H. M., Goh, W. C., ...
Tests performed in different regimes reveal the interplay of two edge-enhancement mechanisms in radiological images taken with coherent synchrotron light. The relative weight of the two mechanisms,...
Collimation-enhanced micro-radiography in real-time (2006)
Hwu, Y., Tsai, W. L., Hsieh, H. H., Je, J. H., Kang, H. S., Kim, I. W., ...
Highly collimated synchrotron sources are the essential ingredient of novel radiology and micro-radiology techniques for materials science. medicine and biology-with contrast based on the refractive...
Nitrogen based magnetic semiconductors (2006)
Elfimov, I. S., Rusydi, A., Csiszar, S. I., Hu, Z., Hsieh, H. H., ...
We describe a possible pathway to new magnetic materials with no conventional magnetic elements present. The substitution of Nitrogen for Oxygen in simple non magnetic oxides leads to holes in N 2$p$...
Orbitally driven spin-singlet dimerization in $S$=1 La$_{4}$Ru$_{2}$O$_{10}$ (2006)
Wu, Hua, Hu, Z., Burnus, T., Denlinger, J. D., Khalifah, P. G., Mandrus, D., ...
Using x-ray absorption spectroscopy at the Ru-$L_{2,3}$ edge we reveal that the Ru$^{4+}$ ions remain in the $S$=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We...
Soft x-ray magnetic circular dichroism study on Gd-doped EuO thin films (2005)
Ott, H., Heise, S. J., Sutarto, R., Hu, Z., Chang, C. F., Hsieh, H. H., ...
We report on the growth and characterization of ferromagnetic Gd-doped EuO thin films. We prepared samples with Gd concentrations up to 11% by means of molecular beam epitaxy under distillation...
Orbital-assisted metal-insulator transition in VO$_{2}$ (2005)
Haverkort, M. W., Hu, Z., Tanaka, A., Reichelt, W., Streltsov, S. V., Korotin, M. A., ...
We found direct experimental evidence for an orbital switching in the V 3d states across the metal-insulator transition in VO$_{2}$. We have used soft-x-ray absorption spectroscopy at the V $L_{2,3}$...
Controlling orbital moment and spin orientation in CoO layers by strain (2005)
Csiszar, S. I., Haverkort, M. W., Hu, Z., Tanaka, A., Hsieh, H. H., ...
We have observed that CoO films grown on different substrates show dramatic differences in their magnetic properties. Using polarization dependent x-ray absorption spectroscopy at the Co L$_{2,3}$...
Aligning spins in antiferromagnetic films using antiferromagnets (2005)
Csiszar, S. I., Haverkort, M. W., Burnus, T., Hu, Z., Tanaka, A., Hsieh, H. H., ...
We have explored the possibility to orient spins in antiferromagnetic thin films with low magnetocrystalline anisotropy via the exchange coupling to adjacent antiferromagnetic films with high...
Different look at the spin state of Co3+ ions in a CoO5 pyramidal coordination (2004)
Hu,Z., Wu,H., Haverkort,M. W., Hsieh,H. H., Lin,H. J., Lorenz,T., ...
Determination of the orbital moment and crystal field splitting in LaTiO$_{3}$ (2004)
Haverkort, M. W., Hu, Z., Tanaka, A., Ghiringhelli, G., Roth, H., Cwik, M., ...
Utilizing a sum-rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO$_3$ is strongly reduced both below and above...
Different look at the spin state of Co3+ ions in a CoO5 pyramidal coordination (2004)
Hu, Z., Wu, H., Haverkort, M. W., Hsieh, H. H., Lin, H. J., Lorenz, T., ...
Magnetic versus crystal field linear dichroism in NiO thin films (2003)
Haverkort, M. W., Csiszar, S. I., Hu, Z., Altieri, S., Tanaka, A., Hsieh, H. H., ...
We have detected strong dichroism in the Ni $L_{2,3}$ x-ray absorption spectra of monolayer NiO films. The dichroic signal appears to be very similar to the magnetic linear dichroism observed for...
A different look at the spin state of Co$^{3+}$ ions in CoO$_{5}$ pyramidal coordination (2003)
Hu, Z., Wu, Hua, Haverkort, M. W., Hsieh, H. H., Lorenz, T., ...
Using soft-x-ray absorption spectroscopy at the Co-$L_{2,3}$ and O-$K$ edges, we demonstrate that the Co$^{3+}$ ions with the CoO$_{5}$ pyramidal coordination in the layered Sr$_2$CoO$_3$Cl compound...
A Universal Intrinsic Scale of Hole Concentration for High-Tc Cuprates (2003)
Honma, T., Hor, P. H., Hsieh, H. H., Tanimoto, M.
We have measured thermoelectric power (TEP) as a function of hole concentration per CuO2 layer, Ppl, in Y1-xCaxBa2Cu3O6 (Ppl = x/2) with no oxygen in the Cu-O chain layer. The room-temperature TEP as...
Direct observation of electron doping in La0.7Ce0.3MnO3 using x-ray absorption spectroscopy (2003)
Mitra,C., Hu,Z., Raychaudhuri,P., Wirth,S., Csiszar,S. I., Hsieh,H. H., ...
Growth and properties of strained VOx thin films with controlled stoichiometry (2003)
Rata, A. D., Chezan, A. R., Hibma, T., Haverkort, M. W., Tjeng, L. H., Hsieh, H. H., ...
We have succeeded in growing epitaxial films of rocksalt VOx on MgO(001) substrates. The oxygen content as a function of oxygen flux was determined using 18O2-RBS and the vanadium valence using XAS....
Direct observation of electron doping in La0.7Ce0.3MnO3 using x-ray absorption spectroscopy (2003)
Mitra, C., Hu, Z., Raychaudhuri, P., Wirth, S., Csiszar, S. I., Hsieh, H. H., ...
Direct observation of electron doping in La0.7Ce0.3MnO3 using x-ray absorption spectroscopy (2002)
Mitra, C., Hu, Z., Raychaudhuri, P., Wirth, S., Csiszar, S. I., Hsieh, H. H., ...
We report on a X-ray absorption spectroscopic (XAS) study on a thin film of La0.7Ce0.3MnO3, a manganite which was previously only speculated to be an electron doped system. The measurements clearly...