The phase diagram of underdoped cuprates in a magnetic field ( H ) is key to understanding the anomalous normal state of these high-temperature superconductors. However, the upper critical field ( H c2 ), the extent of superconducting (SC) phase with vortices, and the role of charge orders at high H remain controversial. Here we study stripe-ordered La-214, i.e., cuprates in which charge orders are most pronounced and zero-field SC transition temperatures T c 0 are lowest. This enables us to explore the vortex phases in a previously inaccessible energy scale window. By combining linear and nonlinear transport techniques sensitive to vortex matter, we determine the T − H phase diagram, directly detect H c2 , and reveal novel properties of the high-field ground state. Our results demonstrate that quantum fluctuations and disorder play a key role as T → 0 , while the high-field ground state is likely a metal, not an insulator, due to the presence of stripes.
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Magnetic field reveals vanishing Hall response in the normal state of stripe-ordered cuprates
Abstract The origin of the weak insulating behavior of the resistivity, i.e. $${\rho }_{xx}\propto {\mathrm{ln}}\,(1/T)$$ ρ x x ∝ ln ( 1 / T ) , revealed when magnetic fields ( H ) suppress superconductivity in underdoped cuprates has been a longtime mystery. Surprisingly, the high-field behavior of the resistivity observed recently in charge- and spin-stripe-ordered La-214 cuprates suggests a metallic, as opposed to insulating, high-field normal state. Here we report the vanishing of the Hall coefficient in this field-revealed normal state for all $$T\ <\ (2-6){T}_{{\rm{c}}}^{0}$$ T < ( 2 − 6 ) T c 0 , where $${T}_{{\rm{c}}}^{0}$$ T c 0 is the zero-field superconducting transition temperature. Our measurements demonstrate that this is a robust fundamental property of the normal state of cuprates with intertwined orders, exhibited in the previously unexplored regime of T and H . The behavior of the high-field Hall coefficient is fundamentally different from that in other cuprates such as YBa 2 Cu 3 O 6+ x and YBa 2 Cu 4 O 8 , and may imply an approximate particle-hole symmetry that is unique to stripe-ordered cuprates. Our results highlight the important role of the competing orders in determining the normal state of cuprates.
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- Award ID(s):
- 1707785
- NSF-PAR ID:
- 10250826
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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A common characteristic of many “overdoped” cuprates prepared with high-pressure oxygen is
T c values ≥ 50 K that often exceed that of optimally doped parent compounds, despite O stoichiometries that place the materials at the edge or outside of the conventional boundary between superconducting and normal Fermi liquid states. X-ray absorption fine-structure (XAFS) measurements at 52 K on samples of high-pressure oxygen (HPO) YSr2Cu2.75Mo0.25O7.54,T c = 84 K show that the Mo is in the (VI) valence in an unusually undistorted octahedral geometry with predominantly Mo neighbors that is consistent with its assigned substitution for Cu in the chain sites of the structure. Perturbations of the Cu environments are minimal, although the Cu X-ray absorption near-edge structure (XANES) differs from that in other cuprates. The primary deviation from the crystal structure is therefore nanophase separation into Mo- and Cu-enriched domains. There are, however, indications that the dynamical attributes of the structure are altered relative to YBa2Cu3O7, including a shift of the Cu-apical O two-site distribution from the chain to the plane Cu sites. Another effect that would influenceT c is the possibility of multiple bands at the Fermi surface caused by the presence of the second phase and the lowering of the Fermi level. -
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In the physics of condensed matter, quantum critical phenomena and unconventional superconductivity are two major themes. In electron-doped cuprates, the low critical field (HC2) allows one to study the putative quantum critical point (QCP) at low temperature and to understand its connection to the long-standing problem of the origin of the high-
TC superconductivity. Here we present measurements of the low-temperature normal-state thermopower (S ) of the electron-doped cuprate superconductor La2−x Cex CuO4(LCCO) fromx = 0.11–0.19. We observe quantum criticalversus behavior over an unexpectedly wide doping range x = 0.15–0.17 above the QCP (x = 0.14), with a slope that scales monotonically with the superconducting transition temperature (TC with H = 0). The presence of quantum criticality over a wide doping range provides a window on the criticality. The thermopower behavior also suggests that the critical fluctuations are linked withTC . Above the superconductivity dome, atx = 0.19, a conventional Fermi-liquidbehavior is found for 40 K. -
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Abstract Experiments investigating magnetic-field-tuned superconductor–insulator transition (HSIT) mostly focus on two-dimensional material systems where the transition and its proximate ground-state phases, often exhibit features that are seemingly at odds with the expected behavior. Here we present a complementary study of a three-dimensional pressure-packed amorphous indium-oxide (InOx) powder where granularity controls the HSIT. Above a low threshold pressure of ∼0.2 GPa, vestiges of superconductivity are detected, although neither a true superconducting transition nor insulating behavior are observed. Instead, a saturation at very high resistivity at low pressure is followed by saturation at very low resistivity at higher pressure. We identify both as different manifestations of anomalous metallic phases dominated by superconducting fluctuations. By analogy with previous identification of the low resistance saturation as a ‘failed superconductor’, our data suggests that the very high resistance saturation is a manifestation of a ‘failed insulator’. Above a threshold pressure of ∼6 GPa, the sample becomes fully packed, and superconductivity is robust, with
T Ctunable with pressure. A quantum critical point atP C∼ 25 GPa marks the complete suppression of superconductivity. For a finite pressure belowP C, a magnetic field is shown to induce a HSIT from a true zero-resistance superconducting state to a weakly insulating behavior. Determining the critical field,H C, we show that similar to the 2D behavior, the insulating-like state maintains a superconducting character, which is quenched at higher field, above which the magnetoresistance decreases to its fermionic normal state value.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41467-021-24000-3
