Who
Riccardo Comin, MIT
Abstract
The quantum electronic state in underdoped copper oxide high temperature superconductors tends to break the translational symmetry of the parent lattice. These symmetry-broken phases are, to varying degrees, intertwined with the superconducting state, which is why understanding their phenomenology can provide an important key to decoding the mechanisms of unconventional superconductivity. Electronic orders come in two main forms – charge/spin stripes and incommensurate charge-density-
waves (CDWs) – but in all cases emerge out of a strongly correlated metallic state. However, early theoretical studies also predicted the emergence of a 'charge crystal' phase in very lightly-doped, insulating states of the CuO 2 planes, which was observed only recently in insulating Bi 2 Sr 2 CuO 6+y , raising new questions on whether such a state is generic to all cuprates. In this talk, I will present results from a combination of resonant X-ray scattering, electronic transport, and muon spin rotation measurements to study electronic orders in the REBa 2 Cu 3 O 7 family (REBCO). By
controlling the concentration of mobile carriers in the CuO 2 planes via rare earth substitution (Pr-for-Y), we could explore the previously uncharted very underdoped limit of REBCO. In the correlated metallic regime around 10% doping, we found a conventional CDW with single ordering vector (CDW-1Q) and resonating exclusively at the Cu-L 3 edge. However, in the magnetic insulator end compound PrBa 2 Cu 3 O 7 , we discovered a multiorbital density wave originating from Cu and Pr orbitals, indicating the persistence of translational symmetry breaking deep in the magnetic insulator ‘Mott’ limit. Our observations of an electronic crystal state in a second cuprate family reveal that this electronic state is a new and potentially ubiquitous form of electronic symmetry breaking in the CuO 2 planes. Ultimately, these findings strongly hint at a strong coupling origin of charge order in the REBCO family and underscore the prominent role of Coulomb-frustrated electronic phase separation across all cuprates.
waves (CDWs) – but in all cases emerge out of a strongly correlated metallic state. However, early theoretical studies also predicted the emergence of a 'charge crystal' phase in very lightly-doped, insulating states of the CuO 2 planes, which was observed only recently in insulating Bi 2 Sr 2 CuO 6+y , raising new questions on whether such a state is generic to all cuprates. In this talk, I will present results from a combination of resonant X-ray scattering, electronic transport, and muon spin rotation measurements to study electronic orders in the REBa 2 Cu 3 O 7 family (REBCO). By
controlling the concentration of mobile carriers in the CuO 2 planes via rare earth substitution (Pr-for-Y), we could explore the previously uncharted very underdoped limit of REBCO. In the correlated metallic regime around 10% doping, we found a conventional CDW with single ordering vector (CDW-1Q) and resonating exclusively at the Cu-L 3 edge. However, in the magnetic insulator end compound PrBa 2 Cu 3 O 7 , we discovered a multiorbital density wave originating from Cu and Pr orbitals, indicating the persistence of translational symmetry breaking deep in the magnetic insulator ‘Mott’ limit. Our observations of an electronic crystal state in a second cuprate family reveal that this electronic state is a new and potentially ubiquitous form of electronic symmetry breaking in the CuO 2 planes. Ultimately, these findings strongly hint at a strong coupling origin of charge order in the REBCO family and underscore the prominent role of Coulomb-frustrated electronic phase separation across all cuprates.
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