Extended pseudogap and suppressed strange metal phase in clean overdoped cuprate superconductor Tl<sub>2</sub>Ba<sub>2</sub>CuO<sub>6+x</sub>
ORAL
Abstract
A microscopic understanding of high-Tc superconductivity in cuprates has remained elusive due to their complexity and multiple competing orders [1]. Studies over the past decades suggest that much of this complexity may arise from weak disorder introduced by doping [2–4], motivating efforts to establish the intrinsic phase diagram of recently discovered “clean” cuprates [5–8]. Recent work on clean underdoped cuprates such as YBa2Cu3O7-x and YBa2Cu4O8 [9] further supports this perspective.
Here we report electrical transport measurements on the clean overdoped cuprate superconductor Tl2Ba2CuO6+x [8]. Single crystals were grown and annealed using established techniques [10], and a focused-ion-beam (FIB) microstructuring process was developed to fabricate mesoscopic transport devices (~10 μm) without degrading sample quality. This enables measurements of intrinsic electronic behavior with well-controlled geometry, minimizing extrinsic effects from disorder or inhomogeneity.
Our in-plane measurements agree quantitatively with previous bulk studies, indicating that T-linearity cannot extend far below Tc at any doping level, while out-of-plane transport reveals new features. Specifically, we observe a low-temperature upturn in the zero-field c-axis resistivity that is suppressed with increasing field and doping. We attribute this feature to the pseudogap, as other conceivable origins—Fermi surface reconstruction, charge order, or a van Hove singularity—lie outside the relevant doping range. These findings demonstrate that the pseudogap persists well beyond the critical doping p*, accompanied by a suppression of strange-metal behavior in clean overdoped Tl2Ba2CuO6+x.
References:
[1] Nature 518, 179–186 (2015).
[2] Phys. Rev. Lett. 119, 216601 (2017).
[3] EPL 56, 870 (2001).
[4] Phys. Rev. Research 2, 013228 (2020).
[5] Nature 447, 565–568 (2007).
[6] Phys. Rev. Lett. 100, 047003 (2008).
[7] Nature 455, 952–955 (2008).
[8] Nature Physics 9, 761–764 (2013).
[9] Nature Communications 16, 3579 (2025).
[10] A W Tyler, PhD Thesis, University of Cambridge (1994).
Here we report electrical transport measurements on the clean overdoped cuprate superconductor Tl2Ba2CuO6+x [8]. Single crystals were grown and annealed using established techniques [10], and a focused-ion-beam (FIB) microstructuring process was developed to fabricate mesoscopic transport devices (~10 μm) without degrading sample quality. This enables measurements of intrinsic electronic behavior with well-controlled geometry, minimizing extrinsic effects from disorder or inhomogeneity.
Our in-plane measurements agree quantitatively with previous bulk studies, indicating that T-linearity cannot extend far below Tc at any doping level, while out-of-plane transport reveals new features. Specifically, we observe a low-temperature upturn in the zero-field c-axis resistivity that is suppressed with increasing field and doping. We attribute this feature to the pseudogap, as other conceivable origins—Fermi surface reconstruction, charge order, or a van Hove singularity—lie outside the relevant doping range. These findings demonstrate that the pseudogap persists well beyond the critical doping p*, accompanied by a suppression of strange-metal behavior in clean overdoped Tl2Ba2CuO6+x.
References:
[1] Nature 518, 179–186 (2015).
[2] Phys. Rev. Lett. 119, 216601 (2017).
[3] EPL 56, 870 (2001).
[4] Phys. Rev. Research 2, 013228 (2020).
[5] Nature 447, 565–568 (2007).
[6] Phys. Rev. Lett. 100, 047003 (2008).
[7] Nature 455, 952–955 (2008).
[8] Nature Physics 9, 761–764 (2013).
[9] Nature Communications 16, 3579 (2025).
[10] A W Tyler, PhD Thesis, University of Cambridge (1994).
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Presenters
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Ayanesh Maiti
- Max Planck Institute for Chemical Physics of Solids