Search results for "Charge density wave"
showing 10 items of 17 documents
Single crystal-like thin films of blue bronze
2021
Abstract Pulsed laser deposition technique was employed to grow thin films of K 0.3 M o O 3 on A l 2 O 3 (1-102) and S r T i O 3 (510) substrates. Structural and imaging characterization revealed good quality films with well oriented grains of few microns in length. Both non-selective (transport) and order-selective (femtosecond pump-probe spectroscopy) probes revealed charge density wave properties that are very close to those of the single crystals. The films exhibit metal-semiconductor phase transition in resistivity, pump-probe data show phase transition at the same temperature as the single crystal and the threshold for the photo-induced phase transition is approximately the same as in…
Ultrafast Metamorphosis of a Complex Charge Density Wave in Tantalumdiselenite
2016
Using ultrafast electron diffraction, we record the transformation between a nearly-commensurate and an incommensurate charge-density-wave in 1T-TaS2, which takes place orders of magnitude faster than previously observed for commensurate-to-incommensurate transitions.
Ultrafast Metamorphosis of a Complex Charge-Density Wave
2015
Modulated phases, commensurate or incommensurate with the host crystal lattice, are ubiquitous in solids. The transition between such phases involves formation and rearrangement of domain walls and is generally slow. Using ultrafast electron diffraction, we directly record the photoinduced transformation between a nearly commensurate and an incommensurate charge-density-wave phase in 1T-TaS(2). The transformation takes place on the picosecond time scale, orders of magnitude faster than previously observed for commensurate-to-incommensurate transitions. The transition speed and mechanism can be linked to the peculiar nanoscale structure of the photoexcited nearly commensurate phase.
Charge density waves in NbSe3: The models and the experimental evidence
2010
a b s t r a c t Charge density wave (CDW) ordering in the prototypical low-dimensional compound NbSe3 is reconsidered. It is shown that the model with two incommensurate modulations, q1 = (0, 0.241, 0) and q2 = (0.5, 0.260, 0.5), localized on type-III and type-I bi-capped trigonal prismatic columns, does not explain details, revealed by various microscopic methods. An alternative explanation, based on the existence of modulated layered nano-domains below both CDW onset temperatures, is suggested. It accounts for the presence of the q2 modulation in the STM images recorded above the T2 CDW transition and for the absence of q2 satellites in the corresponding diffraction patterns. The long per…
Optical control of vibrational coherence triggered by an ultrafast phase transition
2019
Femtosecond time-resolved x-ray diffraction is employed to study the dynamics of the periodic lattice distortion (PLD) associated with the charge-density-wave (CDW) in K0.3MoO3. Using a multi-pulse scheme we show the ability to extend the lifetime of coherent oscillations of the PLD about the undistorted structure through re-excitation of the electronic states. This suggests that it is possible to enter a regime where the symmetry of the potential energy landscape corresponds to the high symmetry phase but the scattering pathways that lead to the damping of coherent dynamics are still controllable by altering the electronic state population. The demonstrated control over the coherence time …
Evolution of structural and electronic properties of TiSe2 under high pressure
2021
A pressure-induced structural phase transition and its intimate link with the superconducting transition was studied for the first time in TiSe2 up to 40 GPa at room temperature using X-ray diffraction, transport measurement, and first-principles calculations. We demonstrate the occurrence of a first-order structural phase transition at 4 GPa from the standard trigonal structure (S.G.P3¯m1) to another trigonal structure (S-G-P3¯c1). Additionally, at 16 GPa, the P3¯c1 phase spontaneously transforms into a monoclinic C2/m phase, and above 24 GPa, the C2/m phase returns to the initial P3¯m1 phase. Electrical transport results show that metallization occurs above 6 GPa. The charge density wave …
Quantum Phases and Spin Liquid Properties of 1T-TaS2
2021
Quantum materials exhibiting magnetic frustration are connected to diverse phenomena including high-Tc superconductivity, topological order and quantum spin liquids (QSLs). A QSL is a quantum phase (QP) related to a quantum-entangled fluid-like state of matter. Previous experiments on QSL candidate materials are usually interpreted in terms of a single QP, although theories indicate that many distinct QPs are closely competing in typical frustrated spin models. Here we report on combined temperature-dependent muon spin relaxation and specific heat measurements for the triangular-lattice QSL candidate material 1T-TaS2 that provide evidence for competing QPs. The measured properties are assig…
Chiral charge order in the superconductor 2H-TaS(2)
2011
Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM
Out-of-plane transport of 1T-TaS2/graphene-based van der Waals heterostructures
2021
Due to their anisotropy, layered materials are excellent candidates for studying the interplay between the in-plane and out-of-plane entanglement in strongly correlated systems. A relevant example is provided by 1T-TaS2, which exhibits a multifaceted electronic and magnetic scenario due to the existence of several charge density wave (CDW) configurations. It includes quantum hidden phases, superconductivity and exotic quantum spin liquid (QSL) states, which are highly dependent on the out-of-plane stacking of the CDW. In this system, the interlayer stacking of the CDW is crucial for the interpretation of the underlying electronic and magnetic phase diagram. Here, thin-layers of 1T-TaS2 are …
X-Ray Crystallographic Analysis of the Charge-Density Wave Modulated Phases in the NbTe4-TaTe4 System
1999
NbTe4 and TaTe4 belong to the important structural family CuAl2 (tl20) characterized by a tetragonal antiprismatic coordination of the minority component. The basic structures were first described by Selte and Kjekshus [1] and Selte and Bjerkelund [2]. In these structures the Te atoms form 1-D infinite columns of stacked tetragonal antiprisms along [001] which are centered by the metal atoms (Figure 1). The arrangement of the antiprismatic columns in the tetragonal a 1 a 2-plane yields short Te-Te contacts, forming Te2 pairs with covalent bonds of about 2.92 A. Thus, following the usual chemical arguments MTe4 (M=Nb,Ta) is a ditelluride of M(IV), i.e. M4+(Te 2 2- )2. The structure is strong…