Microscopic parameters from high-resolution specific heat measurements on superoptimally substituted ${\mathrm{BaFe}}_2{\left({\mathrm{As}}_{1-x}{\mathrm{P}}_x\right)}_2$ single crystals

Journal Article · Tue Jan 19 00:00:00 EST 2016 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.93.014509· OSTI ID:1352558

Diao, Z.; Campanini, D.; Fang, L.; Kwok, W. -K.; Welp, U.; Rydh, A.

We investigate the electronic specific heat of superoptimally substituted BaFe₂(As_1-x P_x)₂ single crystals in the superconducting state using high-resolution nanocalorimetry. From the measurements, we extract the substitution dependence of the condensation energy, superconducting gap Δ, and related microscopic parameters. We find that the anomalous scaling of the specific heat jump ΔC ∝ to T$$3\atop{c}$$ , found in many iron-based superconductors, in this system originates from a T_c-dependent ratio Delta/k_BT_c in combination with a substitution-dependent density of states N(epsilon(F)). A clear enhancement is seen in the effective mass m* as the composition approaches the value that has been associated with a quantum critical point at optimum substitution. However, a simultaneous increase in the superconducting carrier concentration n_s yields a penetration depth lambda that decreases with increasing T_c without sharp divergence at the quantum critical point. Uemura scaling indicates that T_c is governed by the Fermi temperature T_F for this multiband system.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1352558
• Journal Information: Physical Review B, Vol. 93, Issue 1; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY