SU(2) theory of cuprates
Dr Corentin Morice (CEA Paris)
Recent transport experiments in the cuprate superconductors shed new light on the connection between the enigmatic pseudogap phase and the evolution of the electronic dispersion under doping. The latter is known to evolve from Fermi arcs measured by ARPES in the underdoped regime, to a large hole Fermi surface at high doping, as seen e.g. in quantum oscillation measurements. Combined Hall number and resistivity measurements at high magnetic field showed that the carrier density sharply changes from p to 1+p at the pseudogap critical doping p*, linking the opening of the pseudogap to a change in electronic dispersion.
The SU(2) theory of cuprates shows that antiferromagnetic short-range interactions cause the arising of both charge and superconducting orders, which are related by an SU(2) symmetry. The fluctuations associated with this symmetry form a pseudogap phase, which was shown to account for Raman, neutron diffraction and strange metal experimental evidence. Here, we first calculate the spectral functions and transport quantities of the renormalised bands. We show that their evolution with doping matches both spectral and transport measurements. In a second step, we argue that topological defects in the pseudo-spin space related to the SU(2) symmetry enlighten many mysterious properties of the pseudogap phase in under-doped cuprates, in particular the charge modulations seen both at low and high magnetic field and q=0 phase transitions, of both nematic and loop currents characters