Soon-Jae Moon

We have investigated the details of the growth behavior of epitaxially-stabilized 5d perovskite SrIrO3 thin films deposited by using a pulsed laser deposition method. During the deposition,a marked decrease in plume size was observed, which was accompanied by the formation of Irrich conical structures on the surface of the polycrystalline SrIrO3 target. High-resolution X-ray diffraction studies revealed that films thicker than certain thickness exhibited a mixed character of a high-quality phase

Abstract When a magnetic moment is embedded in a metal, it captures nearby itinerant electrons to form a so-called Kondo cloud. When magnetic impurities are sufficiently dense that their individual clouds overlap with each other they are expected to form a correlated electronic ground state. This is known as Kondo condensation and can be considered a magnetic version of Bardeen–Cooper–Schrieffer pair formation. Here, we examine this phenomenon by performing electrical transport and high-precisio

CaTiO3 is a well-known incipient ferroelectric material that does not undergo a ferroelectric phase transition in spite of the intriguing dielectric constant behavior. Especially, unlike a prototypical incipient ferroelectric SrTiO3, the paraelectric state of CaTiO3 cannot be easily destroyed by small perturbations, including cation doping and epitaxial strain. We present that a nearly strain-free epitaxial CaTiO3 film grown at a low oxygen partial pressure exhibits polarizationevoltage hysteres

The structure of dielectric perovskite BaZrO3, long known to be cubic at room temperature without any structural phase transition with variation in temperature, has been recently disputed to have different ground state structures with lower symmetries involving octahedra rotation. Pressure-dependent Raman scattering measurements can identify the hierarchy of energetically-adjacent polymorphs, helping in turn to understand its ground state structure at atmospheric pressure. Here, the Raman scatte

We report on the temperature-dependent optical absorption spectra of an orthorhombic SrIrO3thin film in the energy region between 0.08 and 6 eV. The optical absorption spectra show thecharacteristic spectral features associated with spin-orbit coupling-induced effective total angularmomentum Jeff states. A Drude-like response from the electrons in the Jeff = 1/2 bands isobserved in the energy region below about 0.5 eV followed by an interband transition from the Jeff= 3/2 to the Jeff = 1/2 bands

${\mathrm{SrAs}}_{3}$ is a unique nodal-line semimetal that contains only a single nodal ring in the Brillouin zone, uninterrupted by any trivial bands near the Fermi energy. We performed axis-resolved optical reflection measurements on ${\mathrm{SrAs}}_{3}$ and observed that the optical conductivity exhibits flat absorption up to 129 meV in both the radial and axial directions, confirming the robustness of the universal power-law behavior of the nodal ring. The axis-resolved optical conductivit

We report the effects of deposition temperature on the evolution of defect and second phasesand on the ferroelectric properties of BiFeO3 thin films. We grew BiFeO3 thin films on (001)SrTiO3 substrates by using pulsed laser deposition at temperatures in the range of 570 − 600 Cat intervals of 10 C. We found that defects and a resulting second phase appeared at temperaturesgreater than 590 C. The second phase led to significant changes in the optical absorption and to theappearance of impurity pe

We report on the transport and the core-level X-ray photoemission spectroscopy data of fullystrainedLaTiO3 thin films grown on GdScO3 and SrTiO3 substrates. We observed that LaTiO3thin film grown on GdScO3 showed insulating behavior but that grown on SrTiO3 exhibited ametallic character. We found that while the La 4d photoemission spectra of the two films werenearly the same, their Ti 2p and O 1s data revealed a difference. Our results suggest that straininducedchanges in the Ti-O bonding play a

Abstract We performed polarized reflection and transmission measurements on the layered conducting oxide PdCoO 2 thin films. For the ab-plane, an optical peak near Ω ≈ 750 cm−1 drives the scattering rate γ ∗ (ω) and effective mass m ∗ (ω) of the Drude carrier to increase and decrease respectively for ω ≧ Ω. For the c-axis, a longitudinal optical phonon (LO) is present at Ω as evidenced by a peak in the loss function Im[−1/ε c (ω)]. Further polarized measurements in different light propagation (q

SrAs_{3} is a unique nodal-line semimetal that contains only a single nodal ring in the Brillouin zone, uninterrupted by any trivial bands near the Fermi energy. We performed axis-resolved optical reflection measurements on SrAs_{3} and observed that the optical conductivity exhibits flat absorption up to 129 meV in both the radial and axial directions, confirming the robustness of the universal power-law behavior of the nodal ring. The axis-resolved optical conductivity, in combination with the