Forced Diffusion of Correlated Impurities in the Peierls Conductor o -TaS 3
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Forced Diffusion of Correlated Impurities in Peierls Conductor o-TaS3 V. E. Minakova1) , A. M. Nikitina, S. V. Zaitsev-Zotov Kotelnikov Institute of Radioengineering and Electronics, Russian Academy of Sciences, 125009 Moscow, Russia Submitted 17 July 2020 Resubmitted 31 July 2020 Accepted 1 August 2020
It is shown that in orthorhombic TaS3 with quenching defects, when the temperature changes in the region below the Peierls transition temperature T < TP , forced diffusion of defects arises due to their strong interaction with the charge density wave (CDW). The relationships between the concentration of quenching defects, n, the threshold field of the onset of CDW sliding, ET , and the defect-induced shift of TP are determined: ET ∝ n and ΔTP ∝ n. This set of laws corresponds to the case when quenching defects positions are correlated with the CDW. The ordinary (without thermocycling) diffusion of quenching defects was detected at T ≈ 300 K, its diffusion coefficient and the height of the energy barrier were estimated. This made it possible to clarify the most probable nature of the defects. These are interstitial sulfur impurities introduced during quenching into the van der Waals gap between the chains and partially ordered at T < TP due to interaction with the CDW. This ordering significantly lowers the height of the energy barrier of forced diffusion in comparison with ordinary diffusion when the spatial configuration of the CDW changes during thermocycling. This leads to the appearance of anomalously high low-temperature forced mobility of correlated impurities. DOI: 10.1134/S0021364020180022
Introduction. There are a number of physical systems in which, under certain conditions, spatially ordered electronic superstructures are formed. For instance, charge and spin density waves (CDW and SDW), Wigner crystals, and vortex lattices in type II superconductors in a magnetic field are this kind of materials. The interaction of the superstructures with lattice imperfections (various defects, impurities, etc.) results in a number of effects. Examples of such effects are pinning of the superstructure, which leads to the appearance of a threshold value of the force necessary to begin its sliding, and also the destruction of long-range order, which causes the smearing and suppression of the transition of superstructure formation with an increase in the number of pinning centers. Such a pinning in the case of a Peierls conductor leads to the fact that its current voltage characteristics (IV -curves) are linear in small electric fields E < ET , where ET is the threshold value corresponding to the onset of the CDW sliding [1–4]. ET depends on the concentration of pinning centers, n, and increases with its growth. The temperature of the Peierls transition, TP , on the contrary, decreases with increasing n. In the case of large n, the Peierls transition is smeared out due to loss of the CDW coherence [5].
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This behavior is well studied experimentally for such pinning centers as substitutional impurities [6], growth [7] and rad
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