TY - JOUR

T1 - Wiedemann-Franz Law and Abrupt Change in Conductivity across the Pseudogap Critical Point of a Cuprate Superconductor

AU - Michon, B.

AU - Ataei, A.

AU - Bourgeois-Hope, P.

AU - Collignon, C.

AU - Li, S. Y.

AU - Badoux, S.

AU - Gourgout, A.

AU - Laliberté, F.

AU - Zhou, J. S.

AU - Doiron-Leyraud, Nicolas

AU - Taillefer, Louis

PY - 2018/10/15

Y1 - 2018/10/15

N2 - The thermal conductivity κ of the cuprate superconductor La1.6-xNd0.4SrxCuO4 was measured down to 50 mK in seven crystals with doping from p=0.12 to p=0.24, both in the superconducting state and in the magnetic field-induced normal state. We obtain the electronic residual linear term κ0/T as T→0 across the pseudogap critical point p=0.23. In the normal state, we observe an abrupt drop in κ0/T upon crossing below p, consistent with a drop in carrier density n from 1+p to p, the signature of the pseudogap phase inferred from the Hall coefficient. A similar drop in κ0/T is observed at H=0, showing that the pseudogap critical point and its signatures are unaffected by the magnetic field. In the normal state, the Wiedemann-Franz law, κ0/T=L0/ρ(0), is obeyed at all dopings, including at the critical point where the electrical resistivity ρ(T) is T linear down to T→0. We conclude that the nonsuperconducting ground state of the pseudogap phase at T=0 is a metal whose fermionic excitations carry heat and charge as conventional electrons do.

AB - The thermal conductivity κ of the cuprate superconductor La1.6-xNd0.4SrxCuO4 was measured down to 50 mK in seven crystals with doping from p=0.12 to p=0.24, both in the superconducting state and in the magnetic field-induced normal state. We obtain the electronic residual linear term κ0/T as T→0 across the pseudogap critical point p=0.23. In the normal state, we observe an abrupt drop in κ0/T upon crossing below p, consistent with a drop in carrier density n from 1+p to p, the signature of the pseudogap phase inferred from the Hall coefficient. A similar drop in κ0/T is observed at H=0, showing that the pseudogap critical point and its signatures are unaffected by the magnetic field. In the normal state, the Wiedemann-Franz law, κ0/T=L0/ρ(0), is obeyed at all dopings, including at the critical point where the electrical resistivity ρ(T) is T linear down to T→0. We conclude that the nonsuperconducting ground state of the pseudogap phase at T=0 is a metal whose fermionic excitations carry heat and charge as conventional electrons do.

UR - http://www.scopus.com/inward/record.url?scp=85055214886&partnerID=8YFLogxK

U2 - 10.1103/PhysRevX.8.041010

DO - 10.1103/PhysRevX.8.041010

M3 - Article (Academic Journal)

AN - SCOPUS:85055214886

SN - 2160-3308

VL - 8

JO - Physical Review X

JF - Physical Review X

IS - 4

M1 - 041010

ER -