LAUSR

In hole-doped cuprates there is now compelling evidence that inside the pseudogap phase, charge order breaks translational symmetry. In YBa2Cu3Oy charge order emerges in two steps: a 2D order found at zero field and at high temperature inside the pseudogap phase, and a 3D order that is superimposed below the superconducting transition Tc when superconductivity is weakened by a magnetic field. Several issues still need to be addressed such as the effect of disorder, the relationship between those charge orders and their respective impact on the Fermi surface. Here, we report high magnetic field sound velocity measurements of the 3D charge order in underdoped YBa2Cu3Oy in a large doping range. We found that the 3D charge order exists over the same doping range as its 2D counterpart, indicating an intimate connection between the two distinct orders. Moreover, our data suggest that 3D charge order has only a limited impact on low-lying electronic states of YBa2Cu3Oy.Charge density wave in YBCO: Long range vs short rangeThe long range charge order observed in underdoped YBCO when superconductivity is weakened by a high magnetic field is found to exist over a similar doping range as the short range charge order found above the superconducting critical Tc. F. Laliberté et al. used ultrasound velocity measurements in high magnetic field to thermodynamically detect the transition towards long range charge order in underdoped YBCO in a large doping range. This systematic study reveals the boundary of the long range charge order dome in the T,p phase diagram of YBCO, which extends over the same doping range as the short range order observed at higher temperatures in zero magnetic field. This indicates an intimate connection between the two kinds of charge modulations. Furthermore, a comparison with Hall effect measurements shows that the onset of long range charge order has a limited impact on low-lying electronic states.