Quasi One-dimensional Materials Research Articles

Humidity response of single carbon nanocoil and its temperature sensor independent of humidity and strain

Carbon nanocoil (CNC) is a quasi-one dimensional material with unique helical morphology, which provides abundant sites for the adsorption of water and other gas molecules. Herein, we investigated the humidity response of CNCs, including the response mechanism and further regulation. We used several methods to modify the physical and chemical structures of CNC, including 1200 °C annealing, HCl, NH3H2O and H2O2 treatments, to regulate its humidity response and analyze response mechanism. We experimentally demonstrated the p-type conduction of CNCs and the donor characteristic of the adsorbed water molecules, which are not affected by treatment methods. It is found that NH3H2O treatment greatly suppresses the humidity response (almost no response) without affecting the temperature response of CNCs, while annealing suppresses the humidity and temperature response of CNCs simultaneously. Due to the abundant vacancies, defects and functional groups in CNCs, NH3H2O treatment introduces non-volatile water molecules into CNCs, which prevent further adsorption of water molecules and inhibit the humidity response of CNCs. By this way, we achieved an independent temperature sensor of CNCs with no response to humidity, which paves the way for the device based on single CNCs that is independent of humidity and strain.

Charge density waves in low-dimensional material

Charge density waves (CDWs) have triggered off extensive research in low-dimensional systems. The discovery of CDW offers a new crucial clue to understanding the intrinsic mechanisms of low-dimensional electron-phonon coupling and electron correlation. In addition, the physical properties of low-dimensional material such as magnetism and superconductivity can be fine-tuned with accurately and effectively controlled CDW phase. At the beginning,we briefly introduce the basic properties of CDW in one-dimensional and quasi one-dimensional materials, revealing the physical proprieties of the CDW, for instance, the excited state and the manipulation technologies. Then, focusing on the CDW in a two-dimensional system, we mainly introduce the recent research progress and the generation mechanism of CDW of two-dimensional materials. The interaction between CDW and Mott insulator and between superconductivity and other orders such as spin density wave and pair density wave provide a new perspective to research the multi-electron collective excitation and electron interaction. The manipulation of multi-electron collective excitation and electron-phonon interaction in CDW through doping, high pressure and laser pulse is also introduced and shares similarity with the one-dimensional system. Finally, in this article we propose a potential research application of two dimensional CDW.

A strange strange metal

Physics The so-called strange metal phase appears in the phase diagrams of many quantum materials, including cuprate high-temperature superconductors and heavy fermion compounds. Strange metals frequently occur in the vicinity of antiferromagnetism, suggesting a connection between the two. Now, Shen et al . reveal an unusual strange metal phase near a ferromagnetic quantum critical point in the quasi–one-dimensional material CeRh6Ge4. The researchers observed anomalous transport and thermodynamics properties typical of strange metals near the critical pressure at which the material becomes ferromagnetic. Nature 579 , 51 (2020).

Lattice dynamics of twisted ZnO nanowires under generalized Born–von Karman boundary conditions

Due to their excellent structural flexibility, low dimensional materials allow to modulate their properties by strain engineering. In this work, we illustrate the phonon calculation of deformed quasi-one dimensional nanostructures involving inhomogeneous strain patterns. The key is to employ the generalized Born–von Karman boundary conditions, where the phonon states are characterized with screw and rotational symmetries. We use wurtzite ZnO nanowire (NW) as a representative to demonstrate the validity and efficiency of the present approach. First, we show the equivalence between the phonon dispersions obtained with this approach and that obtained with standard phonon approach. Next, as an application of the present approach, we study the phonon responses of ZnO NWs to twisting deformation. We find that twisting has more influence on the phonon modes resided in the NW shell than those resided around the NW core. For phonon at the NW shell, the modes polarized along the NW axis is more sensitive to twisting than those polarized in the NW radial dimension. Twisting also induces significant reduction in group velocities for a large portion of optical modes, hinting a non-negligible impact on the lattice thermal conductivity. The present approach may be useful to study the strain-tunable thermal properties of quasi-one dimensional materials.

Density matrix renormalization group study of a three-orbital Hubbard model with spin-orbit coupling in one dimension

Using the Density Matrix Renormalization Group technique we study the effect of spin-orbit coupling on a three-orbital Hubbard model in the $(t_{2g})^{4}$ sector and in one dimension. Fixing the Hund coupling to a robust value compatible with some multiorbital materials, we present the phase diagram varying the Hubbard $U$ and spin-orbit coupling $\lambda$, at zero temperature. Our results are shown to be qualitatively similar to those recently reported using the Dynamical Mean Field Theory in higher dimensions, providing a robust basis to approximate many-body techniques. Among many results, we observe an interesting transition from an orbital-selective Mott phase to an excitonic insulator with increasing $\lambda$ at intermediate $U$. In the strong $U$ coupling limit, we find a non-magnetic insulator with an effective angular momentum $\langle(\textbf{J}^{eff})^{2}\rangle \ne 0$ near the excitonic phase, smoothly connected to the $\langle(\textbf{J}^{eff})^{2}\rangle = 0$ regime. We also provide a list of quasi-one dimensional materials where the physics discussed in this publication could be realized.

Electrical and thermal transport in the quasiatomic limit of coupled Luttinger liquids

We introduce a new model for quasi one-dimensional materials, motivated by intriguing but not yet well-understood experiments that have shown two-dimensional polymer films to be promising materials for thermoelectric devices. We consider a two-dimensional material consisting of many one-dimensional systems, each treated as a Luttinger liquid, with weak (incoherent) coupling between them. This approximation of strong interactions within each one-dimensional chain and weak coupling between them is the "quasi-atomic limit." We find integral expressions for the (interchain) transport coefficients, including the electrical and thermal conductivities and the thermopower, and we extract their power law dependencies on temperature. Luttinger liquid physics is manifested in a violation of the Wiedemann-Franz law; the Lorenz number is larger than the Fermi liquid value by a factor between $\gamma^2$ and $\gamma^4$, where $\gamma\geq 1$ is a measure of the electron-electron interaction strength in the system.

Coupling effects of the electric field and bending on the electronic and magnetic properties of penta-graphene nanoribbons.

Quasi one-dimensional materials made from carbon have attracted a lot of attention because of their interesting properties and potential applications in electronic devices. Recently, new kinds of carbon allotropes named as penta-graphene nanoribbons (P-GNRs) have been proposed. By implementing first-principles calculations, P-GNRs exhibit large tunable band gaps under bending stress, and the band gaps of P-GNRs are easier to control than those of GNRs. In addition, the order of spin moments of P-GNRs can transform from ferromagnetic to antiferromagnetic under the coupling effect of the electric field and bending strain, thus resulting in a significant change of magnetism. Therefore, the diverse electronic and magnetic properties highlight the potential applications of P-GNRs in flexible displays, wearable computation electronics and digital memory devices.

Temperature dependence of the NMR relaxation rate1/T1for quantum spin chains

We present results of numerical simulations performed on one-dimensional spin chains in order to extract the so-called relaxation rate $1/T_1$ accessible through NMR experiments. Building on numerical tensor network methods using the Matrix Product States (MPS) formalism, we can follow the non-trivial crossover occurring in critical chains between the high-temperature diffusive classical regime and the low-temperature response described by the Tomonaga-Luttinger liquid (TLL) theory, for which analytical expressions are known. In order to compare analytics and numerics, we focus on a generic spin-$1/2$ XXZ chain which is a paradigm of gapless TLL, as well as a more realistic spin-$1$ anisotropic chain, modelling the DTN material, which can be either in a trivial gapped phase or in a TLL regime induced by an external magnetic field. Thus, by monitoring the finite temperature crossover, we provide quantitative limits on the range of validity of TLL theory, that will be useful when interpreting experiments on quasi one-dimensional materials.

Thermal Conductivity of the One-Dimensional Fermi-Hubbard Model.

We study the thermal conductivity of the one-dimensional Fermi-Hubbard model at a finite temperature using a density matrix renormalization group approach. The integrability of this model gives rise to ballistic thermal transport. We calculate the temperature dependence of the thermal Drude weight at half filling for various interaction strengths. The finite-frequency contributions originating from the fact that the energy current is not a conserved quantity are investigated as well. We report evidence that breaking the integrability through a nearest-neighbor interaction leads to vanishing Drude weights and diffusive energy transport. Moreover, we demonstrate that energy spreads ballistically in local quenches with initially inhomogeneous energy density profiles in the integrable case. We discuss the relevance of our results for thermalization in ultracold quantum-gas experiments and for transport measurements with quasi-one-dimensional materials.

Direct observation of single-electron solitons and Friedel oscillations in a quasi-one dimensional material with incommensurate charge-density waves

We have performed scanning tunneling microscopy experiments in the quasi-one dimensional charge density wave (CDW) system NbSe3, where we could image and study in detail individual solitons corresponding to the self-trapping of a single electron. Our analysis shows that the type of soliton we observed is an “Amplitude Soliton”, characterized by a vanishing CDW amplitude at the soliton center and by a π-shift of its phase along the chain direction. Pairs of solitons or multiple solitons were also observed. Such observations could be made only in the high-temperature CDW phase. Additionally, one-dimensional Friedel oscillations around charged defects could also be imaged and are found to be superimposed to the CDW. The distinction between amplitude solitons and Friedel oscillations can be made without any ambiguity.

Electron transport in high-resistance semiconductor nanowires through two-probe measurements

Since the successful fabrication of semiconductor nanowires, various techniques have been developed to contact these nanowires and to probe their intrinsic electrical properties. Although many novel quasi one-dimensional materials such as Pb(1 - x)Mn(x)Se nanoarrays were recently produced, their intrinsic electron transport properties have not been extensively studied so far. In this work, we demonstrate that an ordinary source-drain configuration of field-effect transistors or the two-probe measurement can be applied to the exploration of the intrinsic properties of nanowires. This two-probe measurement approach also works on highly resistive nanowires without an Ohmic contact issue. By using this method, electron transport behavior, resistivity, and carrier concentrations of ZnO, InP, GaP, and Pb(1 - x)Mn(x)Se semiconductor nanowires have been investigated. Due to the tiny cross-section and few conducting channels, a nanomaterial usually reveals an ultra high resistance. This technique demonstrates a two-probe characterization of nanostructures, paving the simplest way toward electrical characterizations of all high-resistance nanomaterials such as deoxyribonucleic acid (DNA), molecules and organics.

Renormalization group approach for highly anisotropic two-dimensional fermion systems: Application to coupled Hubbard chains

I apply a two-step density-matrix renormalization group method to the anisotropic two-dimensional tight-binding model. This study, which is a prelude to the study of models of quasi-one dimensional materials, shows the potential power of this approach for anisotropic fermionic models. I find a ground-state energy which agrees with the exact value up to four digits for systems as large as $24 \times 25$. This open new opportunities for simulations of fermions in two dimensions.

Issues on the Transport of One Dimensional Quantum Systems

In this paper, we will critically discuss recent theoretical and experimental developments on the transport of one dimensional quantum systems. In particular, we will focus on open issues and controversial results related to the finite temperature dynamics of integrable quantum models. These singular systems are commonly used in the description of quasi-one dimensional materials. They have recently attracted a lot of interest in connection to the interpretation of experiments, specially after the discovery of unusual thermal conductivity in magnetic compounds.

Electronic structure of solids with competing periodic potentials.

When electrons are subject to a potential with two incommensurate periods, translational invariance is lost, and no periodic band structure is expected. However, model calculations based on nearly free one-dimensional electrons and experimental results from high-resolution photoemission spectroscopy on a quasi-one-dimensional material do show dispersing band states with signatures of both periodicities. Apparent band structures are generated by the nonuniform distribution of electronic spectral weight over the complex eigenvalue spectrum.

The spectral properties of quasi-one-dimensional materials : High-resolution ARPES

Photoemission investigations of quasi-one dimensional materials reveal the unconventional electronic properties of these systems. The normal state spectra are incompatible with a Fermi liquid description, and exhibit features consistent with the Luttinger liquid scenario, which describes correlated fermions in 1D. Specific surface effects,, and the tendency to defect-induced localization in these systems, may considerably influence the measured spectral properties.

Specific heat of TSeF-TCNQ

We have measured the specific heat of single crystals of TSeF-TCNQ. Anomalies are observed at T a = 28 K and T b = 33 K, indicating that there are two phase transitions, presumably reflecting the separate condensation of the charge-density-wave on the TSeF and TCNQ conducting chains. The total increase of the specific heat on cooling through both transitions is larger than the value estimated from mean-field theory, as expected for transitions in a quasi-one dimensional material, but, because of the proximity of the two transitions, it is not possible to unambiguously determine the specific heat baseline and hence the magnitude of the specific heat step. A sharp peak in specific heat is also observed at T a ; if the entropy contained in this peak is to be associated with locking of the charge-density-wave phases on the two conducting chains, its large size implies a surprisingly small phase coherent volume.

Fermi liquids and non-Fermi liquids—The view from photoemission

This paper presents an improved Fermi liquid lineshape analysis of the ARPES spectra of 1TTiTe 2, and a brief overview of recent efforts to identify Luttinger liquid type behavior in photoemission spectra of quasi one-dimensional materials such as K 0.3MoO 3

Lattice fluctuations and disorder in quasi-one dimensional materials

We show that the zero-point and thermal lattice motions have a significant effect on the electronic properties of the Peierls-Fröhlich state. The lattice fluctuations can be modelled as intrinsic disorder in the system. Exact analytic expressions are presented for the density of states and localization length in the disordered system. The disorder produces a significant rounding of the density of states compared to that of a rigid lattice. The electronic properties vary on a temperature scale determined by the phonon frequency, ω 2 kf .

Heteroepitaxy Between Lattice Mismatched Materials with Van Der Waals Interactions

ABSTRACTThe lattice matching condition encountered usually in the heteroepitaxial growth has been proved to be relaxed drastically, if one uses the interface having van der Waals nature. Such interface can be realized on a cleaved face of a layered material or a quasi-one dimensional material and on a surface of a dangling-bond-terminated three dimensional material. Various kinds of heterostructures, which cannot be made by conventional growth methods, can be fabricated by using a variety of layered transition metal dichalcogenides, in which there exist superconducting, metallic, semiconducting or insulating layered materials. Moreover those heterostructures have been found to be grown on such an ordinary three-dimensional material as GaAs, if the dangling bonds on its surface are terminated by suitable atoms.

Thermally Assisted Depinning of a Deformable Charge Density Wave

Effect of thermal activations over potential barriers on the charge-density-wave conduction is studied in a simple kinetic model of strong impurity-pinning. Calculated conductivities are characterized by a pseudo-threshold E 0 at a finite electric field, if temperature is not too high. E 0 substantially decreases with increasing temperature. It is suggested that this mechanism of thermally assisted depinning may be responsible for the temperature dependence of the nonlinear conduction experimentally observed in quasi one-dimensional materials at low temperatures.