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We investigate the effect that the temperature dependence of the crystal structure of a two dimensional organic charge-transfer salt has on the low-energy Hamiltonian representation of the electronic structure. For that, we determine the…

Strongly Correlated Electrons · Physics 2012-08-23 Harald O. Jeschke , Mariano de Souza , Roser Valenti , Rudra Sekhar Manna , Michael Lang , John A. Schlueter

We present an X-ray diffraction study of the quasi-2D conductors a-(BEDTTTF)2MHg(SCN), with M=K and Rb. They exhibit a phase transition of the density wave type at TDW=8-10K and 12-13K respectively, evidenced by magnetoresistivity, specific…

Strongly Correlated Electrons · Physics 2007-05-23 P. Foury-Leylekian , S. Ravy , J. -P. Pouget , H. Muller

We have investigated the charge dynamics of VO2 by optical reflectivity measurements. Optical conductivity clearly shows a metal-insulator transition. In the metallic phase, a broad Drude-like structure is observed. On the other hand, in…

Strongly Correlated Electrons · Physics 2009-11-11 K. Okazaki , S. Sugai , Y. Muraoka , Z. Hiroi

We report high-resolution dilatometry studies on single crystals of the Shastry-Sutherland-lattice magnet NdB$_4$ supported by specific heat and magnetometry data. Our dilatometric studies evidence pronounced anomalies at the phase…

We have investigated the transition temperature $T_{\rm c}(H)$ of superconductiv ity in quasi-two-dimensional (Q2D) tight-binding electrons in a strong magnetic field. When the magnetic field is parallel to 2D conducting plane, $T_{\rm…

Superconductivity · Physics 2009-10-31 Mitake Miyazaki , Keita Kishigi , Yasumasa Hasegawa

An analysis of the evolutionary trends in the ground state geometries of Na$_{55}$ to Na$_{62}$ reveals Na$_{58}$, an electronic closed--shell system, shows namely an electronically driven spherical shape leading to a disordered but compact…

Statistical Mechanics · Physics 2015-06-25 Mal-Soon Lee , D. G. Kanhere

The magnetic properties of alkali-metal peroxychromate K$_2$NaCrO$_8$ are governed by the $S = 1/2$ pentavalent chromium cation, Cr$^{5+}$. Specific heat, magnetocalorimetry, ac magnetic susceptibility, torque magnetometry, and inelastic…

The electronic structure of NaFeAs is studied with angle resolved photoemission spectroscopy on high quality single crystals. Large portions of the band structure start to shift around the structural transition temperature, and smoothly…

We have studied the ultrasonic velocity and ac susceptibility of $URu_2Si_2$ in d. c. magnetic fields up to 45T. A significant difference between the constructed H-T phase diagram and that extracted from earlier pulsed fields measurements…

Strongly Correlated Electrons · Physics 2007-05-23 A. Suslov , J. B. Ketterson , D. G. Hinks , Bimal K. Sarma

The anisotropic changes in the electronic structure of a metal-to-insulator transition (MIT) material, RuAs, with two-step phase transition are reported by using polarized optical conductivity [$\sigma(\omega)$] spectra, angle-integrated…

We measured the resistivity and magnetic susceptibility to map out the phase diagram of single crystalline NaFe$_{1-x}$Co$_x$As. Replacement of Fe by Co suppresses both the structural and magnetic transition, while enhances the…

Superconductivity · Physics 2012-06-21 A. F. Wang , X. G. Luo , Y. J. Yan , J. J. Ying , Z. J. Xiang , G. J. Ye , P. Cheng , Z. Y. Li , W. J. Hu , X. H. Chen

The temperature dependence of the integrated optical conductivity I(T) reflects the changes of the kinetic energy as spin and charge correlations develop. It provides a unique way to explore experimentally the kinetic properties of strongly…

Strongly Correlated Electrons · Physics 2009-11-07 Markus Aichhorn , Peter Horsch , Wolfgang von der Linden , Mario Cuoco

The specific heat, magnetic susceptibility and ESR signals of a Na-deficient vanadate Na_xV_2O_5 (x=1.00 - 0.90) were studied in the temperature range 0.07 - 10 K, well below the transition point to a spin-gap state. The contribution of…

Strongly Correlated Electrons · Physics 2009-10-31 A. I. Smirnov , S. S. Sosin , R. Calemczuk , V. Villar , C. Paulsen , M. Isobe , Y. Ueda

The polarized optical reflectance spectra of the quasi two dimensional organic correlated electron system $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]$Y$, $Y =$ Br and Cl are measured in the infrared region. The former shows the…

Superconductivity · Physics 2007-05-23 T. Sasaki , I. Ito , N. Yoneyama , N. Kobayashi , N. Hanasaki , H. Tajima , T. Ito , Y. Iwasa

Temperature-dependent FAR-infrared reflectivity spectra of partially ordered magnetodielectric La2CoMnO6 is presented, from room temperature up to 675 K. A clear first-ordered structural phase transition (SPT) from a monoclinic structure…

Materials Science · Physics 2018-02-22 R. X. Silva , A. Nonato , R. L. Moreira , R. M. Almeida , C. W. A. Paschoal

Structural and magnetic properties of Fe@Pt core-shell nanostructure prepared by a sequential reduction process are reported. Transmission electron microscopy (TEM) shows nearly spherical particles fitting a lognormal size distribution with…

Mesoscale and Nanoscale Physics · Physics 2015-10-29 Kelly L. Pisane , Sobhit K. Singh , Mohindar S. Seehra

Thermopower (S) for anatase TiO2 epitaxial films (n3D: 1E17-1E21 /cm3) and the gate voltage (Vg) dependence of S for thin film transistors (TFTs) based on TiO2 films were investigated to clarify the electronic density of states (DOS) around…

Materials Science · Physics 2010-11-02 Yuki Nagao , Akira Yoshikawa , Kunihito Koumoto , Takeharu Kato , Yuichi Ikuhara , Hiromichi Ohta

We investigate the effect of annealing temperature on the crystalline structure and physical properties of tantalum-pentoxide films grown by radio frequency magnetron sputtering. For this purpose, several tantalum films were deposited and…

Single crystals of (Ca1-xLax)10(Pt3As8)(Fe2As2)5 (x = 0 to 0.182) superconductors have been grown and characterized by X-ray, microprobe, transport and thermodynamic measurements. Features in the magnetic susceptibility, specific heat and…

The electronic and magnetic properties of K$_{2}$CuP$_{2}$O$_{7}$ were investigated by means of susceptibility, specific heat and $^{31}$P nuclear magnetic resonance (NMR) measurements and by LDA band structure calculations. The temperature…

Strongly Correlated Electrons · Physics 2009-11-13 R. Nath , Deepa Kasinathan , H. Rosner , M. Baenitz , C. Geibel