Related papers: Ordered low-temperature structure in K4C60 detecte…
Optical excitation perturbs the balance of phenomena selecting the tilt orientation of domain walls within ferroelectric thin films. The high carrier density induced in a low-strain BaTiO3 thin film by an above-bandgap ultrafast optical…
The structural changes in Sr(0.66)Ba(0.34)Nb2O6 single crystal fibers when the temperature decreases from 295 to 10 K is investigated by dielectric constant measurements and Raman spectroscopy. The anomaly observed in the plot of e is…
We report neutron diffraction data on single crystal PrO2 which reveal a cooperative Jahn-Teller distortion at TD = 120 +/- 2 K. Below this temperature an internal distortion of the oxygen sublattice causes the unit cell of the…
The lacunar spinel GaNb$_4$Se$_8$ is a tetrahedral cluster Mott insulator where spin-orbit coupling on molecular orbitals and Jahn-Teller energy scales are competitive. GaNb$_4$Se$_8$ undergoes a structural and anti-polar ordering…
We present a Raman spectroscopy investigation of the vibrational properties of L-histidine crystals at low temperatures. The temperature dependence of the spectra show discontinuities at 165 K, which we identify with modifications in the…
Alkali-doped fullerides exhibit a wealth of unusual phases that remain controversial by nature. Here we report a cryogenic scanning tunneling microscopy study of the sub-molecular structural and electronic properties of expanded fullerene…
We report on optical measurements of the 1D Heisenberg antiferromagnet KCuF3. The crystal-field excitations of the Cu2+ ions have been observed and their temperature dependence can be understood in terms of magnetic and exchange-induced…
X-ray diffraction experiments were performed on polycrystalline and single-crystal specimens of Ce$_{2}$Fe$_{17}$ at temperatures between 10 K and 300 K. Below $T_{\mathrm{t}}$ = 118$\pm$2 K, additional weak superstructure reflections were…
At room temperature, the normal oxide spinels NiCr_2O_4 and CuCr_2O_4 are tetragonally distorted and crystallize in the I4_1/amd space group due to cooperative Jahn-Teller ordering driven by the orbital degeneracy of tetrahedral Ni$^{2+}$…
With a terahertz time-domain spectrometer (0.3 - 3.0 THz) we have measured the optical conductivity of the type-I clathrate Ba$_8$Ga$_{16}$Sn$_{30}$ at temperatures from 300 K down to 7 K. Independent six spectra superimposed on the Drude…
The ternary uranium compound UCu$_2$Sn with a hexagonal ZrPt$_2$Al-type structure shows a phase transition at 16 K. We reported previously that huge lattice-softening is accompanied by the phase transition, which originates from…
NaNiO$_2$ is a Ni$^{3+}$-containing layered material consisting of alternating triangular networks of Ni and Na cations, separated by octahedrally-coordinated O anions. At ambient pressure, it features a collinear Jahn--Teller distortion…
A sequence of structural transitions occurring in the quasi-one-dimensional (1D) 3d1 system BaVS3 at low temperature was investigated by high resolution synchrotron X-ray diffraction. The orthorhombic Cmc21 structure of the…
Optical transitions of an Er$_2$O$_3$ film on a Si substrate grown by using a metal-organic chemical vapor deposition technique were investigated in a wide temperature (300 K $\sim$ 5 K) and spectral (500 nm and 850 nm) ranges. Numerous…
For the first time, magnetic properties of fullerides have been studied using a torque technique. Rb3C60 single crystal has been investigated in these experiments. It was shown that this method is sensitive to the structural phase…
Cupric oxide single crystal thin films were grown by plasma-assisted molecular beam epitaxy. X-ray diffraction, Raman spectrum and in situ reflection high-energy electron diffraction show that the thin films are 2x2 reconstructed with an…
The infrared reflectivity of a $\rm La_{0.67}Ca_{0.33}MnO_3$ single crystal is studied over a broad range of temperatures (78-340 K), magnetic fields (0-16 T), and wavenumbers (20-9000 cm$^{-1}$). The optical conductivity gradually changes…
This paper focuses on the spectroscopic properties of Cr4+:YAG transparent ceramic. Absorption, excitation, and emission spectra were measured over a temperature range from 5K to 300K. Low-temperature absorption spectra reveal sharp and…
The h_u hole spectral intensity for C60 -> C60+ molecular photoemission is calculated at finite temperature by a parameter-free Lanczos diagonalization of the electron-vibration Hamiltonian, including the full 8 H_g, 6 G_g, and 2 A_g mode…
Infrared reflection and transmission as a function of temperature have been measured on single crystals of Cu$_{3}$Bi(SeO$_{3}$)$_{2}$O$_{2}$Cl. The complex dielectric function and optical properties along all three principal axes of the…