Competing charge density waves and temperature-dependent nesting in 2H-TaSe2

Abstract

Multiple charge density wave (CDW) phases in 2H-TaSe2 are investigated by high-resolution synchrotron x-ray diffraction. In a narrow temperature range immediately above the commensurate CDW transition, we observe a multi-q superstructure with coexisting commensurate and incommensurate order parameters, clearly distinct from the fully incommensurate state at higher temperatures. This multi-q ordered phase, characterized by a temperature hysteresis, is found both during warming and cooling, in contrast to previous reports. In the normal state, the incommensurate superstructure reflection gives way to a broad diffuse peak that persists nearly up to room temperature. Its position provides a direct and accurate estimate of the Fermi surface nesting vector, which evolves non-monotonically and approaches the commensurate position as the temperature is increased. This behavior agrees with our recent observations of the temperature-dependent Fermi surface in the same compound [Phys. Rev. B 79, 125112 (2009)].

References in corpus (7)

• Two energy gaps and Fermi surface 'arcs' in NbSe2
• Pseudogap and charge density waves in two dimensions
• Fermi surface nesting in several transition metal dichalcogenides
• Giant Kohn anomaly and the phase transition in charge density wave ZrTe_3
• Non-monotonic pseudo-gap in high-Tc cuprates
• Relation between the one-particle spectral function and dynamic spin susceptibility in superconducting Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8-\delta }$
• Temperature-dependent Fermi surface of 2H-TaSe2 driven by competing density wave order fluctuations

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• Incommensurate and multiple-$\mathbf{q}$ magnetic misfit order in the frustrated quantum-spin-ladder material antlerite, Cu${}_3$SO${}_4$(OH)${}_4$
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