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Contradictory experiments have been reported about the dimensionality effect on the charge-density-wave transition in 2H NbSe$_2$. While scanning tunnelling experiments on single layers grown by molecular beam epitaxy measure a…

介观与纳米尺度物理 · 物理学 2020-09-02 Raffaello Bianco , Lorenzo Monacelli , Matteo Calandra , Francesco Mauri , Ion Errea

The X-ray diffraction, Raman and infrared spectroscopies and magnetic measurements were used to explore the correlated changes of the structure, lattice dynamics and magnetic properties of the LuFeO3 nanoparticles, which appear in…

We provide a detailed study of the reflectivity of multiferroic TbMnO_3 for wave numbers from 40 cm^{-1} to 1000 cm^{-1} and temperatures 5 K < T < 300 K. Excitations are studied for polarization directions E || a, the polarization where…

强关联电子 · 物理学 2010-01-22 M. Schmidt , Ch. Kant , T. Rudolf , F. Mayr , A. A. Mukhin , A. M. Balbashov , J. Deisenhofer , A. Loidl

We present LDA+U calculations of high temperature elastic properties of bridgmanite with composition (Mg$_{(1-x)}$Fe$_{x}^{2+}$)SiO$_3$ for $0\le{x}\le0.125$. Results of elastic moduli and acoustic velocities for the Mg-end member (x=0)…

Ferroelectric ceramics (Ba0.85Ca0.15)(Ti0.9Zr0.1-xSnx)O3 (x=0.00, 0.02, 0.04, 0.06) were prepared by a sol-gel method. Structural investigation revealed the co-existence of tetragonal (P4mm) and orthorhombic (Pmm2) symmetries at room…

Polycrystalline YMn1-xFexO3 (YMFO_x) (0 <= x <= 0.1) compounds have been prepared in single phase and characterized by synchrotron X-ray diffraction, X-ray absorption near edge spectroscopy, magnetization, and dielectric measurements.…

材料科学 · 物理学 2017-07-26 Sonu Namdeo , A. K. Sinha , M. N. Singh , A. M. Awasthi

We revealed the anomalous temperature behavior of the giant dielectric permittivity and unusual frequency dependences of the pyroelectric response of the fine-grained ceramics prepared by the spark plasma sintering of the ferroelectric…

We study the anisotropic in-plane optical conductivity of detwinned Ba(Fe1-xCox)2As2 single crystals for x=0, 2.5% and 4.5% in a broad energy range (3 meV-5 eV) across their structural and magnetic transitions. For temperatures below the…

强关联电子 · 物理学 2016-11-25 A. Lucarelli , A. Dusza , A. Sanna , S. Massidda , J. -H. Chu , I. R. Fisher , L. Degiorgi

The observed correlation of oxygen vacancies and room temperature ferromagnetic ordering in Co doped ZnO1-o nanoparticles reported earlier (Naeem et al Nanotechnology 17, 2675-2680) has been further explored by transport and optical…

材料科学 · 物理学 2007-12-10 M. Naeem , S. K. Hasanain , A. Mumtaz

The resistivity in the ferromagnetic state of flux-grown La_{2/3}(Pb,Ca)_{1/3}MnO_3 single crystals, measured in magnetic fields up to 7 T, reveals a strong quadratic temperature dependence at and above 50 K. At lower temperatures, this…

强关联电子 · 物理学 2009-10-30 M. Jaime , P. Lin , M. B Salamon , P. Han

We have found a remarkable increase (up to 60 %) of the dielectric constant with the onset of magnetic order at 42 K in the metastable orthorhombic structures of YMnO3 and HoMnO3 that proves the existence of a strong magneto-dielectric…

强关联电子 · 物理学 2009-11-10 B. Lorenz , Y. Q. Wang , Y. Y. Sun , C. W. Chu

The magnetic susceptibility between 1.5 and 800 K, the infrared reflectivity at room temperature and the temperature dependence of the dielectric constant at mm-wavelengths are reported for single crystalline BiFeO3. A well developed…

强关联电子 · 物理学 2010-07-22 Jun Lu , M Schmidt , P Lunkenheimer , A Pimenov , A A Mukhin , V D Travkin , A Loidl

We present a first-principles study of the relationship between stress, temperature and electronic properties in piezoelectric ZnO. Our method is a plane wave pseudopotential implementation of density functional theory and density…

材料科学 · 物理学 2009-10-31 Nicola A. Hill , Umesh Waghmare

Dielectric properties of {\alpha}-MoO3 are investigated by a combination of valence electron-energy loss spectroscopy and ab initio calculation at the random phase approximation level with the inclusion of local-field effects (LFE). A…

材料科学 · 物理学 2013-09-27 Luc Lajaunie , Florent Boucher , Rémi Dessapt , Philippe Moreau

We systematically studied in-plane optical conductivity of FeSe$_{1-x}$Te$_{x}$ thin films fabricated on CaF$_{2}$ substrates for $x$ = 0, 0.1, 0.2, and 0.4. This system shows a large enhancement of superconducting transition temperature…

超导电性 · 物理学 2021-08-04 M. Nakajima , K. Yanase , M. Kawai , D. Asami , T. Ishikawa , F. Nabeshima , Y. Imai , A. Maeda , S. Tajima

We present local structural evidence for the existence of charge inhomogeneities at low temperature in underdoped and optimally doped La_2-xSr_xCuO_4. The inhomogeneities disappear for x > 0.2. The evidence for the charge inhomogeneities…

超导电性 · 物理学 2007-05-23 S. J. L. Billinge , E. S. Bozin , M. Gutmann , H. Takagi

Dielectric behavior and conductivity mechanism in lead-free (100-x)(Li0.12Na0.88)NbO3-xBaTiO3 (0 to x to 40) piezoelectric ceramics were investigated using impedance spectroscopy over a wide temperature (-100 oC to500 oC) and frequency…

材料科学 · 物理学 2017-06-13 Supratim Mitra , Ajit R Kulkarni

The structural and magnetic properties of Fe$_{1-x}$Ni$_x$~($x$ = 0.32, 0.36, 0.40, 0.50) alloys have been investigated using synchrotron based x-ray diffraction (XRD) technique with x-rays of wavelength 0.63658 \AA\ down to 50 K…

We have investigated the crystal structure and magnetic properties for polycrystalline samples of LaMn1-xFexO3+y, in the whole range x=0.0 to x=1.0, prepared by solid state reaction in air. All samples show the ORT-2 orthorhombic structure…

强关联电子 · 物理学 2009-11-13 O. F. de Lima , J. A. H. Coaquira , R. L. de Almeida , L. B. de Carvalho , S. K. Malik

We measure the temperature-dependent carrier density and resistivity of the topological surface state of thin exfoliated Bi2Se3 in the absence of bulk conduction. When the gate-tuned chemical potential is near or below the Dirac point the…