Thermodynamic signature of a magnetic-field-driven phase transition within the superconducting state of an underdoped high-temperature superconductor

Abstract

More than a quarter century after the discovery of the high temperature superconductor (HTS) YBa${}_2$Cu${}_3$O${}_{6+\delta }$ (YBCO) studies continue to uncover complexity in its phase diagram. In addition to HTS and the pseudogap there is growing evidence for multiple phases with boundaries which are functions of temperature ($T$), doping (p) and magnetic field. Here we report the low temperature electronic specific heat (C${}_{elec}$) of YBCO6.47 (p=0.08) up to a magnetic field (H) of 34.5 teslas (T), a poorly understood region of the underdoped H-$T$-p phase space. We observe two regimes: below a characteristic magnetic field H'$\approx$10 T, C${}_{elec}/T$ obeys an expected H${}^{1/2}$ behavior, however, near H' there is a sharp inflection followed by a linear-in-H behavior. H' rests deep within the superconducting phase and the linear-in-H behavior is observed in the zero resistance regime. In the limit of zero temperature, C${}_{elec}/T$ is proportional to the zero-energy electronic density of states. Thus this inflection is evidence of a magnetic-field-driven quantum phase transition.

10 pages, 5 figures

References in corpus (10)

• Long-range incommensurate charge fluctuations in (Y,Nd)Ba2Cu3O(6+x)
• Phase competition in trisected superconducting dome
• Emergence of charge order from the vortex state of a high temperature superconductor
• Lifshitz critical point in the cuprate superconductor YBa2Cu3Oy from high-field Hall effect measurements
• Competing charge, spin, and superconducting orders in underdoped YBa2Cu3Oy
• Planes, Chains, and Orbits: Quantum Oscillations and High Magnetic Field Heat Capacity in Underdoped YBCO
• Extending Universal Nodal Excitations Optimizes Superconductivity in Bi2Sr2CaCu2O8+d
• Vortex Lattice Melting and Hc2 in underdoped YBa2Cu3Oy
• Quantum Oscillations in the mixed state of d-wave superconductor
• Berry phases and the intrinsic thermal Hall effect in high temperature cuprate superconductors