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Fully mapping the Fermi surface of a compound provides a clear picture of its fundamental properties. Through thermoelectric measurements of the underdoped cuprate YBa₂Cu₃O_y, this study shows evidence for a second Fermi pocket, consistent with charge–density–wave Fermi surface reconstruction.

Decreasing the doping of a cuprate superconductor below a certain critical value causes its critical temperature to fall, however the reason for this has been unclear. Sensitive measurements of the Nernst effect in yttrium barium copper oxide suggest it is the result of competition with an emerging stripe phase.

The observation of quantum oscillations in the electrical resistance of YBa₂Cu₃O_6.5, is reported, establishing the existence of a well-defined Fermi surface in the ground state of underdoped copper oxides (once superconductivity is suppressed by a magnetic field). The low oscillation frequency reveals a Fermi surface made of small pockets, in contrast to the large cylinder characteristic of the overdoped regime.

An electron pocket exists in the Fermi-surface of the high temperature superconductor YBa₂Cu₃O_y, but its origin is unknown. Here, YBa₂Cu₃O_y and La_1.8−xEu_0.2Sr_xCuO₄ are both shown to exhibit Fermi-surface reconstruction, and in the latter, this is due to stripe order, suggesting that the same mechanism exists in YBa₂Cu₃O_y.

The point at which a magnetic field kills superconductivity in the cuprates has been difficult to measure. Grissonnanche et al. use thermal conductivity measurements to reliably determine this field and find that it drops suddenly below some critical doping, suggesting the onset of a new competing phase.

The first spatially resolved measurements of gap formation in a high-T_c superconductor are reported. Over a wide range of doping (0.16 to 0.22), it is found that pairing gaps nucleate in nanoscale regions above T_c. These regions proliferate as the temperature is lowered, resulting in a spatial distribution of gap sizes in the superconducting state.

High-temperature superconductors exhibit pseudogap behaviour that remains of unknown origin, despite many years of intensive study. Here the authors study the onset of the pseudogap under pressure, providing evidence that it requires a hole-like Fermi surface and constraining future theoretical developments.

The observation of a negative Hall resistance in the magnetic-field-induced normal state of underdoped 'YBCO'materials, which reveals that these pockets are electron-like rather than hole-like. It is proposed that these electron pockets most probably arise from a reconstruction of the Fermi surface caused by the onset of a density-wave phase, as is thought to occur in the electron-doped copper oxides near the onset of antiferromagnetic order.

The two-dimensional atomic layers of black phosphorus may be exfoliated to create devices with desirable electronic transport properties. Here, the authors observe two-dimensional quantum transport in black phosphorus quantum wells, protected from oxidation by encapsulation in a polymer layer.

Electrons in the non-superconducting state of cuprates can exhibit unusual transport behaviour. Now, analysis of experimental data shows that the magnetoresistance in this state is conventional, but influenced by an anisotropic scattering rate.

The recent discovery of charge order in YBa₂Cu₃O_y was unexpected. A systematic study of the evolution of this phenomenon as a function of magnetic field conducted by Wu et al. reveals how the competition between charge order and superconductivity may actually be universal to the underdoped cuprates.

Different probes have found different superconducting pairing states in different iron-based high-temperature superconductors. Now transport measurements suggest that pressure drives the superconducting state in KFe₂As₂ from d-wave to s-wave.

In the study of high-transition-temperature (high-T_c) copper oxide superconductors, a fundamental question is what symmetries are broken when the pseudogap phase sets in below a temperature T*. A large in-plane anisotropy of the Nernst effect is now observed in a high-T_c copper oxide superconductor that sets in precisely at T* throughout the doping phase diagram. It is concluded that the pseudogap phase is an electronic state that strongly breaks four-fold rotational symmetry.

Low-temperature measurements of the Hall effect in cuprate materials in which superconductivity is suppressed by high magnetic fields show that the pseudogap is not related to the charge ordering that has been seen at intermediate doping levels, but is instead linked to the antiferromagnetic Mott insulator at low doping.

A transport study of overdoped cuprates reveals a resistivity that is linear as the temperature approaches 0 K, and is associated with a universal scattering rate.

Thermal transport measurements show that there is a thermal Hall effect in the out-of-plane direction in two cuprates in the pseudogap regime. This indicates that phonons are carrying the heat and that they have a handedness of unknown origin.

The so-called pseudogap phase in hole-doped cuprate superconductors is associated with an unusually large thermal Hall effect that attains unprecedented levels as the parent Mott insulator is approached.

Measurements of the specific heat of two cuprate materials at low temperature in magnetic fields large enough to suppress superconductivity and over a wide doping range reveal that the pseudogap phase of cuprates ends at a quantum critical point.