Heat capacity through the magnetic-field-induced resistive transition in an underdoped high-temperature superconductor

Abstract

Specific heat of a material is a measure of heat necessary to raise the temperature of a given amount of material, typically a gram or a mol, by 1 Kelvin. Near absolute zero, this bulk thermodynamic quantity is a sensitive probe of the low energy excitations of a complex quantum

Chemical potential oscillations from nodal Fermi surface pocket in the underdoped high-temperature superconductor YBa2Cu3O6+x

“…Complementary photoemission experiments at zero field [14][15][16] , optical conductivity experiments up to 8 T, and high field heat capacity 27 experiments indicate a concentration of density-ofstates at the Fermi level solely at the nodal location in momentum space. Taken together with the persistence of quantum oscillations unaltered in form down to low fields ~22 T where the d-wave superconducting gap is well developed, the quasi-two-dimensional Fermi surface pocket that gives rise to multiple frequency components observed by quantum oscillations in underdoped YBa 2 Cu 3 O 6 + x is likely connected with the nodal region of the Brillouin zone.…”

“…The Fermi surface pocket responsible for quantum oscillations is likely located at the nodal region, given that these oscillations persist down to low magnetic fields, where the d-wave superconducting gap is well developed, whereas complementary experiments up to these fields [14][15][16]27 find a concentration in the density-of-states at the Fermi level at the nodes of the superconducting wavefunction. Translational symmetry-breaking models proposed thus far are either nodal-antinodal (for example, refs 11,12), which would be inconsistent with the current experimental results, or comprise solely nodal hole pockets 13 , which would be difficult to reconcile with negative Hall and Seebeck effect 4,20 , leaving us with a dilemma.…”

“…We consider complementary experiments: photoemission experiments at zero field [14][15][16] , optical conductivity experiments up to 8 T (refs 25,26), and high field heat capacity experiments (ref. 27) indicate a solely nodal concentration of the density-ofstates at the Fermi level. Given that the form of quantum oscillations persist unchanged down to 22 T where the d-wave superconducting gap is well developed, indications are that the observed quasi-twodimensional Fermi surface pocket is located at the nodal region of the Brillouin zone.…”

Emergence of charge order from the vortex state of a high-temperature superconductor

“…Remarkably, this field scale ARTICLE is similar to H c2 , as defined from transport measurements in these samples 14,[18][19][20] , indicating that the growth of the amplitude of the charge order is controlled by the decrease of the superconducting order parameter. Although the precise value of H c2 is a matter of debate 21 , a dip of H c2 near p ¼ 0.115-0.12 and values in the range 24-60 T appear to be robust conclusions. Furthermore, this dip of H c2 is paralleled by both a minimum of H charge (Fig.…”

A very cool birthday

“…4); scanning tunnelling microscopy to image bound states within ordered vortices in Ba 0.6 K 0.4 Fe 2 As 2 (ref. 5); and the specific heat of YBa 2 Cu 3 O 6.56 in magnetic fields up to 45 T, which shows quantum oscillations 6,7 . On the theory side, there's also a paper 8 looking at the relative contribution of spin and orbital polarization to the magnetic state in BaFe 2 As 2 .…”