In underdoped cuprates, the interplay of the pseudogap, superconductivity, and charge and spin ordering can give rise to exotic quantum states, including the pair density wave (PDW), in which the ...superconducting (SC) order parameter is oscillatory in space. However, the evidence for a PDW state remains inconclusive and its broader relevance to cuprate physics is an open question. To test the interlayer frustration, the crucial component of the PDW picture, we perform transport measurements on charge- and spin-stripe-ordered La
Eu
Sr
CuO
and La
Nd
Sr
CuO
in perpendicular magnetic fields (H
), and also with an additional field applied parallel to CuO
layers (H
). We detect several phenomena predicted to arise from the existence of a PDW, including an enhancement of interlayer SC phase coherence with increasing H
. These data also provide much-needed transport signatures of the PDW in the regime where superconductivity is destroyed by quantum phase fluctuations.
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.
The phase diagram of underdoped cuprates in a magnetic field (
) is key to understanding the anomalous normal state of these high-temperature superconductors. However, the upper critical field (
), ...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
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
-
phase diagram, directly detect
, and reveal novel properties of the high-field ground state. Our results demonstrate that quantum fluctuations and disorder play a key role as
→
, while the high-field ground state is likely a metal, not an insulator, due to the presence of stripes.
Do charge modulations compete with electron pairing in high-temperature copper oxide superconductors? We investigated this question by suppressing superconductivity in a stripe-ordered cuprate ...compound at low temperature with high magnetic fields. With increasing field, loss of three-dimensional superconducting order is followed by reentrant two-dimensional superconductivity and then an ultraquantum metal phase. Circumstantial evidence suggests that the latter state is bosonic and associated with the charge stripes. These results provide experimental support to the theoretical perspective that local segregation of doped holes and antiferromagnetic spin correlations underlies the electron-pairing mechanism in cuprates.
The dynamics of charge-ordered states is one of the key issues in underdoped cuprate high-temperature superconductors, but static short-range charge-order (CO) domains have been detected in almost ...all cuprates. We probe the dynamics across the CO (and structural) transition in La1.48 Nd0.4 Sr0.12 CuO4 by measuring nonequilibrium charge transport, or resistance R as the system responds to a change in temperature and to an applied magnetic field. We find evidence for metastable states, collective behavior, and criticality. The collective dynamics in the critical regime indicates strong pinning by disorder. Surprisingly, nonequilibrium effects, such as avalanches in R , are revealed only when the critical region is approached from the charge-ordered phase. Our results on La1.48 Nd0.4 Sr0.12 CuO4 provide the long-sought evidence for the fluctuating order across the CO transition, and also set important constraints on theories of dynamic stripes.
Magnetoresistance (MR) was measured in a La
1.48
Nd
0.4
Sr
0.12
CuO
4
single crystal in perpendicular magnetic fields
H
up to 9 T in the region of the structural transition from the low-temperature ...orthorhombic (LTO) to low-temperature tetragonal (LTT) phase. The hysteretic MR exhibits discrete jumps or avalanches only when the transition is approached from the LTT phase, and only during the first field sweep. The properties of the hysteresis are found to be independent of the field driving rate. The results are consistent with the presence of magnetostructural domains coupled with the charge degrees of freedom.
The dynamics of charge-ordered states is one of the key issues in underdoped cuprate high-temperature superconductors, but static short-range charge-order (CO) domains have been detected in almost ...all cuprates. We probe the dynamics across the CO (and structural) transition in La_{1.48}Nd_{0.4}Sr_{0.12}CuO_{4} by measuring nonequilibrium charge transport, or resistance R as the system responds to a change in temperature and to an applied magnetic field. We find evidence for metastable states, collective behavior, and criticality. The collective dynamics in the critical regime indicates strong pinning by disorder. Surprisingly, nonequilibrium effects, such as avalanches in R, are revealed only when the critical region is approached from the charge-ordered phase. Our results on La_{1.48}Nd_{0.4}Sr_{0.12}CuO_{4} provide the long-sought evidence for the fluctuating order across the CO transition, and also set important constraints on theories of dynamic stripes.
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